loader: ghlvl#79, Fix to not report unsupported WSI surface extensions on Linux

Also fix issue where loader would advertise support for these extensions even if
the ICD or layers doesn't support it.  Now ICD must report surface extensions
for the loader to report them.  And on Linux if loader support for a given
surface extension (eg Mir) is compiled out then loader doesn't report it.

Change-Id: I51e302a32f5431f4893a3795ff31be60e9263f43
3 files changed