build: Check for GLES3/gl3ext.h existence

Some OpenGL drivers do not ship this but use GLES2/gl2ext.h instead.
This is also in line with Khronos's recommendations

https://bugzilla.gnome.org/show_bug.cgi?id=781885

diff --git a/gst-libs/gst/gl/gstglapi.h b/gst-libs/gst/gl/gstglapi.h
index 3ce1e03dc6f8541bb1977bfcacbf2cc8d3f1844c..4196e839e2d1df751082321de8d9d02b62a925d4 100644 (file)
--- a/gst-libs/gst/gl/gstglapi.h
+++ b/gst-libs/gst/gl/gstglapi.h
@@ -38,7 +38,10 @@
 # else
 #  if GST_GL_HAVE_GLES3
 #   include <GLES3/gl3.h>
-#   include <GLES3/gl3ext.h>
+#   if GST_GL_HAVE_GLES3EXT3_H
+#    include <GLES3/gl3ext.h>
+#   endif
+#   include <GLES2/gl2ext.h>
 #  else
 #   include <GLES2/gl2.h>
 #   include <GLES2/gl2ext.h>