Unix: Remove now unnecessary I/O defines, cleanup

- `LIBC_FILEIO_ENABLED` wasn't defined anywhere, even in _other platforms_.
- `NO_NETWORK` is also never defined. It probably isn't enough anyway to
  disable network APIs in the current codebase.
- `UNIX_SOCKET_UNAVAILABLE` is never defined in this code but used by some
  other platforms, clarify that.
- `NO_STATVFS` can be removed as Android supports it since API level 19,
  which is our current min SDK level. It's also only used for
  `DirAccessUnix::get_space_left()` which is anyway overridden by
  `DirAccessJAndroid::get_space_left()` so it shouldn't make a difference.
  * Fixed documentation for `DirAccess.get_space_left()`.
- `NO_FCNTL` is likely also a remnant of early Android days, in current NDK
  r23 it seems to be available. Also cleaned up unused `fcntl.h` includes.
- `NO_ALLOCA` is never defined, and we use alloca in many places now.

8 files changed, 18 insertions, 26 deletions

diff --git a/platform/android/detect.py b/platform/android/detect.py
index e541aa0373..3876089575 100644
--- a/platform/android/detect.py
+++ b/platform/android/detect.py
@@ -171,7 +171,7 @@ def configure(env: "Environment"):
             "-fpic -ffunction-sections -funwind-tables -fstack-protector-strong -fvisibility=hidden -fno-strict-aliasing".split()
         )
     )
-    env.Append(CPPDEFINES=["NO_STATVFS", "GLES_ENABLED"])
+    env.Append(CPPDEFINES=["GLES_ENABLED"])
 
     if get_min_sdk_version(env["ndk_platform"]) >= 24:
         env.Append(CPPDEFINES=[("_FILE_OFFSET_BITS", 64)])
@@ -193,7 +193,7 @@ def configure(env: "Environment"):
     env.Append(LINKFLAGS="-Wl,-soname,libgodot_android.so")
 
     env.Prepend(CPPPATH=["#platform/android"])
-    env.Append(CPPDEFINES=["ANDROID_ENABLED", "UNIX_ENABLED", "NO_FCNTL"])
+    env.Append(CPPDEFINES=["ANDROID_ENABLED", "UNIX_ENABLED"])
     env.Append(LIBS=["OpenSLES", "EGL", "GLESv2", "android", "log", "z", "dl"])
 
     if env["vulkan"]:
diff --git a/platform/linuxbsd/display_server_x11.cpp b/platform/linuxbsd/display_server_x11.cpp
index 81fc941608..1ef1deb971 100644
--- a/platform/linuxbsd/display_server_x11.cpp
+++ b/platform/linuxbsd/display_server_x11.cpp
@@ -49,10 +49,14 @@
 #include "drivers/gles3/rasterizer_gles3.h"
 #endif
 
+#include <dlfcn.h>
 #include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include <X11/Xatom.h>
 #include <X11/Xutil.h>
@@ -66,17 +70,6 @@
 #define _NET_WM_STATE_REMOVE 0L // remove/unset property
 #define _NET_WM_STATE_ADD 1L // add/set property
 
-#include <dlfcn.h>
-#include <fcntl.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-//stupid linux.h
-#ifdef KEY_TAB
-#undef KEY_TAB
-#endif
-
 #undef CursorShape
 #include <X11/XKBlib.h>
 
diff --git a/platform/linuxbsd/os_linuxbsd.cpp b/platform/linuxbsd/os_linuxbsd.cpp
index f4e94f1a91..4cbd9722ad 100644
--- a/platform/linuxbsd/os_linuxbsd.cpp
+++ b/platform/linuxbsd/os_linuxbsd.cpp
@@ -42,12 +42,10 @@
 #include <mntent.h>
 #endif
 
+#include <dlfcn.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-
-#include <dlfcn.h>
-#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/utsname.h>
diff --git a/platform/macos/dir_access_macos.h b/platform/macos/dir_access_macos.h
index 920e69ef3e..c76b2835e8 100644
--- a/platform/macos/dir_access_macos.h
+++ b/platform/macos/dir_access_macos.h
@@ -31,16 +31,16 @@
 #ifndef DIR_ACCESS_MACOS_H
 #define DIR_ACCESS_MACOS_H
 
-#if defined(UNIX_ENABLED) || defined(LIBC_FILEIO_ENABLED)
+#if defined(UNIX_ENABLED)
+
+#include "core/io/dir_access.h"
+#include "drivers/unix/dir_access_unix.h"
 
 #include <dirent.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 
-#include "core/io/dir_access.h"
-#include "drivers/unix/dir_access_unix.h"
-
 class DirAccessMacOS : public DirAccessUnix {
 protected:
 	virtual String fix_unicode_name(const char *p_name) const override;
@@ -51,6 +51,6 @@ protected:
 	virtual bool is_hidden(const String &p_name) override;
 };
 
-#endif // UNIX ENABLED || LIBC_FILEIO_ENABLED
+#endif // UNIX ENABLED
 
 #endif // DIR_ACCESS_MACOS_H
diff --git a/platform/macos/dir_access_macos.mm b/platform/macos/dir_access_macos.mm
index 3373cada1f..22ebac2db4 100644
--- a/platform/macos/dir_access_macos.mm
+++ b/platform/macos/dir_access_macos.mm
@@ -30,7 +30,7 @@
 
 #include "dir_access_macos.h"
 
-#if defined(UNIX_ENABLED) || defined(LIBC_FILEIO_ENABLED)
+#if defined(UNIX_ENABLED)
 
 #include <errno.h>
 
@@ -78,4 +78,4 @@ bool DirAccessMacOS::is_hidden(const String &p_name) {
 	return [hidden boolValue];
 }
 
-#endif // UNIX_ENABLED || LIBC_FILEIO_ENABLED
+#endif // UNIX_ENABLED
diff --git a/platform/uwp/os_uwp.h b/platform/uwp/os_uwp.h
index 0c1c4a793a..c1df7827cd 100644
--- a/platform/uwp/os_uwp.h
+++ b/platform/uwp/os_uwp.h
@@ -42,9 +42,9 @@
 #include "servers/rendering/renderer_compositor.h"
 #include "servers/rendering_server.h"
 
-#include <fcntl.h>
 #include <io.h>
 #include <stdio.h>
+
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
diff --git a/platform/windows/display_server_windows.h b/platform/windows/display_server_windows.h
index d85d6364bd..3523e8b3d1 100644
--- a/platform/windows/display_server_windows.h
+++ b/platform/windows/display_server_windows.h
@@ -61,9 +61,9 @@
 #include "gl_manager_windows.h"
 #endif
 
-#include <fcntl.h>
 #include <io.h>
 #include <stdio.h>
+
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <windowsx.h>
diff --git a/platform/windows/os_windows.h b/platform/windows/os_windows.h
index 491de2266f..419871f8bf 100644
--- a/platform/windows/os_windows.h
+++ b/platform/windows/os_windows.h
@@ -40,6 +40,7 @@
 #include "drivers/winmidi/midi_driver_winmidi.h"
 #include "key_mapping_windows.h"
 #include "servers/audio_server.h"
+
 #ifdef XAUDIO2_ENABLED
 #include "drivers/xaudio2/audio_driver_xaudio2.h"
 #endif
@@ -49,10 +50,10 @@
 #include "platform/windows/vulkan_context_win.h"
 #endif
 
-#include <fcntl.h>
 #include <io.h>
 #include <shellapi.h>
 #include <stdio.h>
+
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #include <windowsx.h>