[cogl] tests: Mark test_framebuffer_get_bits as only working on GL

[Neil Roberts <nroberts src gnome org>]

commit cfb0859cab843b000f4baa3ca155a245730edcfa
Author: Neil Roberts <neil linux intel com>
Date:   Mon Jan 21 18:39:55 2013 +0000

    tests: Mark test_framebuffer_get_bits as only working on GL
    
    It looks like it's not meant to be valid to create a framebuffer with
    an alpha-only texture as a render target on GLES. Since the following
    Mesa commit, this requirement is now enforced so that the
    test_framebuffer_get_bits test fails:
    
    http://cgit.freedesktop.org/mesa/mesa/commit/?id=cf300eaa
    
    Reviewed-by: Robert Bragg <robert linux intel com>

 tests/conform/test-conform-main.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/tests/conform/test-conform-main.c b/tests/conform/test-conform-main.c
index 8f2f2d5..389f611 100644
--- a/tests/conform/test-conform-main.c
+++ b/tests/conform/test-conform-main.c
@@ -98,7 +98,9 @@ main (int argc, char **argv)
   ADD_TEST (test_bitmask, 0, 0);
 
   ADD_TEST (test_offscreen, 0, 0);
-  ADD_TEST (test_framebuffer_get_bits, TEST_REQUIREMENT_OFFSCREEN, 0);
+  ADD_TEST (test_framebuffer_get_bits,
+            TEST_REQUIREMENT_OFFSCREEN | TEST_REQUIREMENT_GL,
+            0);
 
   ADD_TEST (test_point_size, 0, 0);
   ADD_TEST (test_point_sprite,