opengl: Check GL_EXT_debug_marker before using it.

The old code just use eglGetProcAddress to get function pointers
without checking if GL_EXT_debug_marker is supported. This doesn't
work for some implementation like MESA. If GL_EXT_debug_marker isn't
supported, reset those function pointers to gl_noop.

Bug: 155935219
Test: manual - Run dEQP-GLES2.functional.debug_marker#random on ARCVM

Change-Id: I93fa8fb419ccde46fef6dd9a2a4ec84f15db3284