Fix egl.h compatiblity.

We should include logic for defining EGL prototypes when no other
preference is specified.

Bug: angleproject:3706
Change-Id: Ie1b5ea6150c7c998a9fe71cf5ee7353dca4ae7ba
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1706908
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>

include/EGL/README.md

diff --git a/include/EGL/README.md b/include/EGL/README.md
index 519ef3e..577ec08 100644
--- a/include/EGL/README.md
+++ b/include/EGL/README.md
@@ -6,9 +6,18 @@
 
 1. Install **Python 3** (not 2) with the **lxml** addon. You can do this using `pip install lxml` from your Python's Scripts folder.
 1. Clone [https://github.com/KhronosGroup/EGL-Registry.git](https://github.com/KhronosGroup/EGL-Registry.git).
-1. Edit `EGL-Registry/api/genheaders.py`:
-
+1. Edit `EGL-Registry/api/genheaders.py` and add the following under `glesProtoPrefixStrings`:
+```# EGL headers use a protection mechanism similar to GLES.
+eglProtoPrefixStrings = [
+    '#ifndef EGL_EGL_PROTOTYPES',
+    '#define EGL_EGL_PROTOTYPES 1',
+    '#endif',
+    ''
+]
+```
+4. Also in `EGL-Registry/api/genheaders.py`:
    1. Look for the section titled `# EGL API - EGL/egl.h (no function pointers, yet @@@)`
+   1. Set `prefixText` to `prefixStrings + eglPlatformStrings + eglProtoPrefixStrings + genDateCommentString`
    1. Change `genFuncPointers   = False,` to `genFuncPointers   = True,`
    1. Change `protectProto      = False,` to `protectProto      = 'nonzero',`
    1. Change `protectProtoStr   = 'EGL_EGLEXT_PROTOTYPES',` to `protectProtoStr   = 'EGL_EGL_PROTOTYPES',`

include/EGL/egl.h

diff --git a/include/EGL/egl.h b/include/EGL/egl.h
index 21cb210..6a19661 100644
--- a/include/EGL/egl.h
+++ b/include/EGL/egl.h
@@ -33,12 +33,16 @@
 ** used to make the header, and the header can be found at
 **   http://www.khronos.org/registry/egl
 **
-** Khronos $Git commit SHA1: 4136522c4d $ on $Git commit date: 2018-12-06 03:51:22 -0800 $
+** Khronos $Git commit SHA1: d738c39fe2 $ on $Git commit date: 2019-06-14 16:17:31 -0600 $
 */
 
 #include <EGL/eglplatform.h>
 
-/* Generated on date 20181214 */
+#ifndef EGL_EGL_PROTOTYPES
+#define EGL_EGL_PROTOTYPES 1
+#endif
+
+/* Generated on date 20190716 */
 
 /* Generated C header for:
  * API: egl