Blind fix to wxiOS build after strike-through fixes.

This should correct build breakage caused by r77695.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77700 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Request hardware accelerated GL under OS X only if it's available.

Otherwise wxGLCanvas creation just fails completely when it isn't, e.g. when
running inside a VM.

Closes #16555.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@77701 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775