[cogl] Clear the color bits of the textures in the color mask test

[Neil Roberts <nroberts src gnome org>]

commit e7cdb1b11b47c81fe9e9a4815a3a2085343e03e8
Author: Luca Bruno <lucabru src gnome org>
Date:   Wed Sep 28 20:48:45 2011 +0200

    Clear the color bits of the textures in the color mask test
    
    Uninitialized textures could contain random bits. That makes the test
    fail as glColorMask is used to let only one of the RGB pass through.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=660387
    
    Reviewed-by: Neil Roberts <neil linux intel com>

 tests/conform/test-color-mask.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)
---
diff --git a/tests/conform/test-color-mask.c b/tests/conform/test-color-mask.c
index d3817ef..389a41d 100644
--- a/tests/conform/test-color-mask.c
+++ b/tests/conform/test-color-mask.c
@@ -92,11 +92,14 @@ test_cogl_color_mask (TestUtilsGTestFixture *fixture,
 {
   TestUtilsSharedState *shared_state = data;
   TestState state;
+  CoglColor bg;
   int i;
 
   state.width = cogl_framebuffer_get_width (shared_state->fb);
   state.height = cogl_framebuffer_get_height (shared_state->fb);
 
+  cogl_color_init_from_4ub (&bg, 0, 0, 0, 255);
+
   for (i = 0; i < NUM_FBOS; i++)
     {
       state.tex[i] = cogl_texture_new_with_size (128, 128,
@@ -105,6 +108,12 @@ test_cogl_color_mask (TestUtilsGTestFixture *fixture,
 
 
       state.fbo[i] = cogl_offscreen_new_to_texture (state.tex[i]);
+
+      /* Clear the texture color bits */
+      cogl_push_framebuffer (state.fbo[i]);
+      cogl_clear (&bg, COGL_BUFFER_BIT_COLOR);
+      cogl_pop_framebuffer ();
+
       cogl_framebuffer_set_color_mask (state.fbo[i],
                                        i == 0 ? COGL_COLOR_MASK_RED :
                                        i == 1 ? COGL_COLOR_MASK_GREEN :