Update to the latest versions of the GL and EGL headers.

Add GLES 3.1 and 3.2 headers.

Remove GLES 3.0 extension headers and entry point files.

Re-land fixes double define from different style defines in libGLESv2.gypi
and other projects.

Re-land fixes missing defines in angle_util project in gn.

Change-Id: I1952413cd4390e6f5450df809f8f5867bf6f49e2
Reviewed-on: https://chromium-review.googlesource.com/299771
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/BUILD.gn b/BUILD.gn
index 671a97e..28f23ff 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -84,8 +84,9 @@
     "include/GLES2/gl2ext.h",
     "include/GLES2/gl2platform.h",
     "include/GLES3/gl3.h",
-    "include/GLES3/gl3ext.h",
     "include/GLES3/gl3platform.h",
+    "include/GLES3/gl31.h",
+    "include/GLES3/gl32.h",
     "include/GLSLANG/ShaderLang.h",
     "include/KHR/khrplatform.h",
   ]
@@ -220,7 +221,7 @@
     defines += [ "ANGLE_USE_X11" ]
   }
   defines += [
-    "GL_GLEXT_PROTOTYPES=",
+    "GL_GLEXT_PROTOTYPES",
   ]
 
   if (is_win) {
@@ -388,6 +389,11 @@
     sources += rebase_path(util_gypi.util_x11_sources, ".", "util")
   }
 
+  defines = [
+    "GL_GLEXT_PROTOTYPES",
+    "EGL_EGLEXT_PROTOTYPES",
+  ]
+
   configs += [
     ":internal_config",
     ":debug_annotations_config",