Fix warnings about unused variables [-Wunused-variable]

Fixes the following GCC 5 warnings:
```
drivers/gles2/rasterizer_scene_gles2.cpp:1139:15: warning: unused variable 'offset' [-Wunused-variable]
drivers/gles2/rasterizer_scene_gles2.cpp:1205:39: warning: unused variable 'multi_mesh' [-Wunused-variable]
drivers/gles2/rasterizer_storage_gles2.cpp:359:7: warning: unused variable 'srgb' [-Wunused-variable]
drivers/gles2/shader_gles2.cpp:1016:45: warning: unused variable 'texture_hints' [-Wunused-variable]
editor/animation_track_editor.cpp:776:9: warning: unused variable 'keys_to' [-Wunused-variable]
editor/editor_inspector.cpp:273:7: warning: unused variable 'vs_height' [-Wunused-variable]
editor/editor_themes.cpp:202:10: warning: unused variable 'begin_time' [-Wunused-variable]
editor/editor_themes.cpp:239:10: warning: unused variable 'end_time' [-Wunused-variable]
editor/plugins/animation_blend_tree_editor_plugin.cpp:726:17: warning: unused variable 'an' [-Wunused-variable]
editor/plugins/script_text_editor.cpp:1278:8: warning: unused variable 'fold_state' [-Wunused-variable]
main/main.cpp:132:13: warning: 'use_vsync' defined but not used [-Wunused-variable]
modules/cvtt/image_compress_cvtt.cpp:231:8: warning: unused variable 'y_end' [-Wunused-variable]
modules/cvtt/image_compress_cvtt.cpp:311:6: warning: unused variable 'shift' [-Wunused-variable]
modules/gdscript/gdscript_editor.cpp:58:7: warning: unused variable 'th' [-Wunused-variable]
modules/gridmap/grid_map.cpp:1084:6: warning: unused variable 'ofs' [-Wunused-variable]
modules/theora/video_stream_theora.cpp:442:9: warning: unused variable 'tr' [-Wunused-variable]
modules/visual_script/visual_script_editor.cpp:2606:6: warning: unused variable 'count' [-Wunused-variable]
modules/visual_script/visual_script_editor.cpp:2829:6: warning: unused variable 'seq_count' [-Wunused-variable]
modules/visual_script/visual_script_editor.cpp:2844:24: warning: unused variable 'vnode_function' [-Wunused-variable]
modules/websocket/lws_peer.cpp:122:12: warning: unused variable 'peer_data' [-Wunused-variable]
modules/websocket/lws_peer.cpp:135:12: warning: unused variable 'peer_data' [-Wunused-variable]
modules/websocket/lws_peer.cpp:63:12: warning: unused variable 'peer_data' [-Wunused-variable]
modules/websocket/lws_peer.cpp:91:12: warning: unused variable 'peer_data' [-Wunused-variable]
platform/android/export/export.cpp:763:16: warning: unused variable 'node_size' [-Wunused-variable]
scene/gui/rich_text_label.cpp:850:10: warning: unused variable 'x_ofs' [-Wunused-variable]
scene/gui/text_edit.cpp:653:8: warning: unused variable 'tab_w' [-Wunused-variable]
scene/resources/bit_mask.cpp:186:6: warning: unused variable 'i' [-Wunused-variable]
scene/resources/mesh.cpp:549:20: warning: '_array_name' defined but not used [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:107:10: warning: unused variable 'v2' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:108:10: warning: unused variable 'v3' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:109:10: warning: unused variable 'v4' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:110:10: warning: unused variable 'v5' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:111:10: warning: unused variable 'v0n' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:112:10: warning: unused variable 'v1n' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:113:10: warning: unused variable 'v2n' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:114:10: warning: unused variable 'v3n' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:115:10: warning: unused variable 'v4n' [-Wunused-variable]
servers/audio/audio_rb_resampler.cpp:116:10: warning: unused variable 'v5n' [-Wunused-variable]
servers/visual/default_mouse_cursor.xpm:2:21: warning: 'default_mouse_cursor_xpm' defined but not used [-Wunused-variable]
```

3 files changed, 0 insertions, 6 deletions

diff --git a/drivers/gles2/rasterizer_scene_gles2.cpp b/drivers/gles2/rasterizer_scene_gles2.cpp
index 56605a9fe5..2007d11b98 100644
--- a/drivers/gles2/rasterizer_scene_gles2.cpp
+++ b/drivers/gles2/rasterizer_scene_gles2.cpp
@@ -1136,8 +1136,6 @@ void RasterizerSceneGLES2::_setup_geometry(RenderList::Element *p_element, Raste
 								bone_weight[3] = (weight_ptr[3] / (float)0xFFFF);
 							}
 
-							size_t offset = i * 12;
-
 							Transform transform;
 
 							Transform bone_transforms[4] = {
@@ -1202,7 +1200,6 @@ void RasterizerSceneGLES2::_setup_geometry(RenderList::Element *p_element, Raste
 		} break;
 
 		case VS::INSTANCE_MULTIMESH: {
-			RasterizerStorageGLES2::MultiMesh *multi_mesh = static_cast<RasterizerStorageGLES2::MultiMesh *>(p_element->owner);
 			RasterizerStorageGLES2::Surface *s = static_cast<RasterizerStorageGLES2::Surface *>(p_element->geometry);
 
 			glBindBuffer(GL_ARRAY_BUFFER, s->vertex_id);
diff --git a/drivers/gles2/rasterizer_storage_gles2.cpp b/drivers/gles2/rasterizer_storage_gles2.cpp
index adf07c2e4f..059c334b94 100644
--- a/drivers/gles2/rasterizer_storage_gles2.cpp
+++ b/drivers/gles2/rasterizer_storage_gles2.cpp
@@ -356,7 +356,6 @@ void RasterizerStorageGLES2::texture_allocate(RID p_texture, int p_width, int p_
 	GLenum type;
 
 	bool compressed = false;
-	bool srgb = false;
 
 	if (p_flags & VS::TEXTURE_FLAG_USED_FOR_STREAMING) {
 		p_flags &= ~VS::TEXTURE_FLAG_MIPMAPS; // no mipies for video
diff --git a/drivers/gles2/shader_gles2.cpp b/drivers/gles2/shader_gles2.cpp
index 216c911a6c..5f4a3fd01c 100644
--- a/drivers/gles2/shader_gles2.cpp
+++ b/drivers/gles2/shader_gles2.cpp
@@ -1013,8 +1013,6 @@ void ShaderGLES2::use_material(void *p_material) {
 	int tc = material->textures.size();
 	Pair<StringName, RID> *textures = material->textures.ptrw();
 
-	ShaderLanguage::ShaderNode::Uniform::Hint *texture_hints = material->shader->texture_hints.ptrw();
-
 	for (int i = 0; i < tc; i++) {
 
 		Pair<ShaderLanguage::DataType, Vector<ShaderLanguage::ConstantNode::Value> > value;