Revert "Add an EGL_ANGLE_surface_orientation extension."

Compilation warnings on clang.

This reverts commit 18cc14b5951842ede85c06dcbc0bba230bcedc45.

Change-Id: If58047486116e34ef30c4b317d3fb47cd2349d15
Reviewed-on: https://chromium-review.googlesource.com/319822
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>
diff --git a/src/libANGLE/Config.cpp b/src/libANGLE/Config.cpp
index d511df3..c558b31 100644
--- a/src/libANGLE/Config.cpp
+++ b/src/libANGLE/Config.cpp
@@ -57,8 +57,7 @@
       transparentType(EGL_NONE),
       transparentRedValue(0),
       transparentGreenValue(0),
-      transparentBlueValue(0),
-      optimalOrientation(0)
+      transparentBlueValue(0)
 {
 }
 
@@ -252,9 +251,6 @@
               case EGL_MAX_PBUFFER_WIDTH:         match = config.maxPBufferWidth >= attributeValue;                   break;
               case EGL_MAX_PBUFFER_HEIGHT:        match = config.maxPBufferHeight >= attributeValue;                  break;
               case EGL_MAX_PBUFFER_PIXELS:        match = config.maxPBufferPixels >= attributeValue;                  break;
-              case EGL_OPTIMAL_SURFACE_ORIENTATION_ANGLE:
-                  match = config.optimalOrientation == attributeValue;
-                  break;
               default: UNREACHABLE();
             }