Whitelist opengles2 headers for ppapi presubmit

The opengles2 interface headers are generated automatically by the command
buffer generator script, instead of the ppapi idl script.
So skip the .h <-> .idl matching for those.

BUG=None

Review URL: https://codereview.chromium.org/143903019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246482 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246482