wflinfo: Build on Mac

I tested that wflinfo doesn't break the build on Mac. Despite building,
though, it doesn't work.

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
cgl: Make waffle_get_proc_address() work

There is no CGLGetProcAddress, so waffle_get_proc_address() always
emitted an error.  However, this patch changes it to follow the
principle of least surprise. The only supported API on CGL is OpenGL, so
assume the user called waffle_get_proc_address() to obtain an OpenGL
function pointer and get it with dlsym().

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>
Merge branch 'wflinfo-mac'

This series gets wflinfo working on Mac.

On Mac we now have the same insight as provided by glxinfo on Linux.
Here's the info from my MacBook Pro:

Waffle platform: cgl
Waffle api: gl
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: AMD Radeon HD 6750M OpenGL Engine
OpenGL version string: 4.1 ATI-1.14.21
OpenGL context flags: FORWARD_COMPATIBLE
OpenGL extensions: GL_ARB_blend_func_extended GL_ARB_draw_buffers_blend
  GL_ARB_draw_indirect GL_ARB_ES2_compatibility
  GL_ARB_explicit_attrib_location GL_ARB_gpu_shader5
  GL_ARB_instanced_arrays GL_ARB_internalformat_query
  GL_ARB_occlusion_query2 GL_ARB_sample_shading GL_ARB_sampler_objects
  GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding
  GL_ARB_shader_subroutine GL_ARB_shading_language_include
  GL_ARB_tessellation_shader GL_ARB_texture_buffer_object_rgb32
  GL_ARB_texture_cube_map_array GL_ARB_texture_gather
  GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui
  GL_ARB_texture_storage GL_ARB_texture_swizzle GL_ARB_timer_query
  GL_ARB_transform_feedback2 GL_ARB_transform_feedback3
  GL_ARB_vertex_type_2_10_10_10_rev GL_ARB_viewport_array
  GL_EXT_debug_label GL_EXT_debug_marker GL_EXT_texture_compression_s3tc
  GL_EXT_texture_filter_anisotropic GL_EXT_texture_mirror_clamp
  GL_EXT_texture_sRGB_decode GL_APPLE_client_storage
  GL_APPLE_container_object_shareable GL_APPLE_flush_render
  GL_APPLE_object_purgeable GL_APPLE_rgb_422 GL_APPLE_row_bytes
  GL_APPLE_texture_range GL_ATI_texture_mirror_once GL_NV_texture_barrier