Fix warnings about set but unused variables [-Wunused-but-set-variable]

Fixes the following GCC 5 warnings:
```
drivers/gles2/rasterizer_canvas_gles2.cpp:814:8: warning: variable 'rt_size' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:2270:11: warning: variable 'vp_height' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:2673:22: warning: variable 'e' set but not used [-Wunused-but-set-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:715:7: warning: variable 'no_cull' set but not used [-Wunused-but-set-variable]
drivers/gles2/shader_gles2.cpp:693:14: warning: variable 'cc' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_canvas_gles3.cpp:1226:8: warning: variable 'rt_size' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_scene_gles3.cpp:3039:10: warning: variable 'contrib' set but not used [-Wunused-but-set-variable]
drivers/gles3/rasterizer_scene_gles3.cpp:4504:32: warning: variable 'vp_height' set but not used [-Wunused-but-set-variable]
editor/editor_inspector.cpp:272:9: warning: variable 'guide_color' set but not used [-Wunused-but-set-variable]
editor/editor_themes.cpp:1067:14: warning: variable 'alpha3' set but not used [-Wunused-but-set-variable]
editor/editor_themes.cpp:263:8: warning: variable 'script_bg_color' set but not used [-Wunused-but-set-variable]
editor/plugins/collision_shape_2d_editor_plugin.cpp:326:11: warning: variable 'cpoint' set but not used [-Wunused-but-set-variable]
editor/plugins/mesh_editor_plugin.cpp:72:9: warning: variable 'size' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:471:12: warning: variable 'mpos' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:89:8: warning: variable 'basetype_color' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:90:8: warning: variable 'type_color' set but not used [-Wunused-but-set-variable]
editor/plugins/shader_editor_plugin.cpp:92:8: warning: variable 'string_color' set but not used [-Wunused-but-set-variable]
modules/visual_script/visual_script_editor.cpp:2521:7: warning: variable 'seq_connect' set but not used [-Wunused-but-set-variable]
platform/android/export/export.cpp:580:12: warning: variable 'styles_count' set but not used [-Wunused-but-set-variable]
platform/android/export/export.cpp:584:12: warning: variable 'styles_offset' set but not used [-Wunused-but-set-variable]
platform/osx/export/export.cpp:464:9: warning: variable 'zerr' set but not used [-Wunused-but-set-variable]
scene/2d/tile_map.cpp:260:10: warning: variable 'tcenter' set but not used [-Wunused-but-set-variable]
scene/3d/light.cpp:166:7: warning: variable 'editor_ok' set but not used [-Wunused-but-set-variable]
scene/3d/navigation.cpp:566:11: warning: variable 'closest_navmesh' set but not used [-Wunused-but-set-variable]
scene/gui/rich_text_label.cpp:869:8: warning: variable 'size' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:705:14: warning: variable 'xform' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:706:8: warning: variable 'ss' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:726:14: warning: variable 'xform' set but not used [-Wunused-but-set-variable]
scene/main/viewport.cpp:727:8: warning: variable 'ss' set but not used [-Wunused-but-set-variable]
scene/resources/material.cpp:430:7: warning: variable 'using_world' set but not used [-Wunused-but-set-variable]
servers/visual/shader_language.cpp:2026:7: warning: variable 'all_const' set but not used [-Wunused-but-set-variable]
servers/visual/visual_server_scene.cpp:1383:28: warning: variable 'z_max_cam' set but not used [-Wunused-but-set-variable]
```

Also fixes two [-Wunused-value] warnings:
```
scene/gui/text_edit.cpp:4405:20: warning: statement has no effect [-Wunused-value]
servers/visual/visual_server_scene.cpp:905:48: warning: value computed is not used [-Wunused-value]
```

Some of those are bugs and need further work, they are identified with
`// FIXME` comments.

2 files changed, 7 insertions, 7 deletions

diff --git a/platform/android/export/export.cpp b/platform/android/export/export.cpp
index e74693893d..056a3e62e0 100644
--- a/platform/android/export/export.cpp
+++ b/platform/android/export/export.cpp
@@ -577,11 +577,11 @@ class EditorExportAndroid : public EditorExportPlatform {
 		uint32_t ofs = 8;
 
 		uint32_t string_count = 0;
-		uint32_t styles_count = 0;
+		//uint32_t styles_count = 0;
 		uint32_t string_flags = 0;
 		uint32_t string_data_offset = 0;
 
-		uint32_t styles_offset = 0;
+		//uint32_t styles_offset = 0;
 		uint32_t string_table_begins = 0;
 		uint32_t string_table_ends = 0;
 		Vector<uint8_t> stable_extra;
@@ -631,16 +631,16 @@ class EditorExportAndroid : public EditorExportPlatform {
 					int iofs = ofs + 8;
 
 					string_count = decode_uint32(&p_manifest[iofs]);
-					styles_count = decode_uint32(&p_manifest[iofs + 4]);
+					//styles_count = decode_uint32(&p_manifest[iofs + 4]);
 					string_flags = decode_uint32(&p_manifest[iofs + 8]);
 					string_data_offset = decode_uint32(&p_manifest[iofs + 12]);
-					styles_offset = decode_uint32(&p_manifest[iofs + 16]);
+					//styles_offset = decode_uint32(&p_manifest[iofs + 16]);
 					/*
 					printf("string count: %i\n",string_count);
 					printf("flags: %i\n",string_flags);
 					printf("sdata ofs: %i\n",string_data_offset);
 					printf("styles ofs: %i\n",styles_offset);
-	*/
+					*/
 					uint32_t st_offset = iofs + 20;
 					string_table.resize(string_count);
 					uint32_t string_end = 0;
diff --git a/platform/osx/export/export.cpp b/platform/osx/export/export.cpp
index b0232e2990..27b4fdc228 100644
--- a/platform/osx/export/export.cpp
+++ b/platform/osx/export/export.cpp
@@ -461,7 +461,7 @@ Error EditorExportPlatformOSX::export_project(const Ref<EditorExportPreset> &p_p
 				fi.internal_fa = info.internal_fa;
 				fi.external_fa = info.external_fa;
 
-				int zerr = zipOpenNewFileInZip(dst_pkg_zip,
+				zipOpenNewFileInZip(dst_pkg_zip,
 						file.utf8().get_data(),
 						&fi,
 						NULL,
@@ -472,7 +472,7 @@ Error EditorExportPlatformOSX::export_project(const Ref<EditorExportPreset> &p_p
 						Z_DEFLATED,
 						Z_DEFAULT_COMPRESSION);
 
-				zerr = zipWriteInFileInZip(dst_pkg_zip, data.ptr(), data.size());
+				zipWriteInFileInZip(dst_pkg_zip, data.ptr(), data.size());
 				zipCloseFileInZip(dst_pkg_zip);
 			}
 		}