appleglx: Improve error reporting if CGLChoosePixelFormat() didn't find any matching pixel formats.

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
(cherry picked from commit 002a3a74273b81dfb226e1c3f0a8c18525ed0af4)
darwin: Write errors in choosing the pixel format to the crash log

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
(cherry picked from commit 9eb1d36c978a9b15ae2e999c630492dfffd7f165)
darwin: Guard Core Profile usage behind a testing envvar

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
(cherry picked from commit 04ce3be4010305902cc5ae81e8e0c8550d043a1e)