Add several missing header guard comments

These were causing build failures under GCC.

Change-Id: Iba19ed166f909fe559d19731f31849770619f412
Reviewed-on: https://chromium-review.googlesource.com/218580
Reviewed-by: Shannon Woods <shannonwoods@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>
diff --git a/src/libGLESv2/formatutils.h b/src/libGLESv2/formatutils.h
index b53cd93..25106a5 100644
--- a/src/libGLESv2/formatutils.h
+++ b/src/libGLESv2/formatutils.h
@@ -103,4 +103,4 @@
 
 }
 
-#endif LIBGLESV2_FORMATUTILS_H_
+#endif // LIBGLESV2_FORMATUTILS_H_
diff --git a/src/libGLESv2/renderer/IndexRangeCache.h b/src/libGLESv2/renderer/IndexRangeCache.h
index 0c41c0f..a7d91e0 100644
--- a/src/libGLESv2/renderer/IndexRangeCache.h
+++ b/src/libGLESv2/renderer/IndexRangeCache.h
@@ -61,4 +61,4 @@
 
 }
 
-#endif LIBGLESV2_RENDERER_INDEXRANGECACHE_H
+#endif // LIBGLESV2_RENDERER_INDEXRANGECACHE_H
diff --git a/src/libGLESv2/renderer/d3d/d3d11/RenderTarget11.h b/src/libGLESv2/renderer/d3d/d3d11/RenderTarget11.h
index ba9f76e..8218295 100644
--- a/src/libGLESv2/renderer/d3d/d3d11/RenderTarget11.h
+++ b/src/libGLESv2/renderer/d3d/d3d11/RenderTarget11.h
@@ -51,4 +51,4 @@
 
 }
 
-#endif LIBGLESV2_RENDERER_RENDERTARGET11_H_
+#endif // LIBGLESV2_RENDERER_RENDERTARGET11_H_