bitmap-pixbuf: Fix the CoglBitmap wrapper for the STB fallback
bitmap-pixbuf: Fix the CoglBitmap wrapper for the STB fallback

The fallback code using stb-image.c was missed out in the upgrade to
cogl_bitmap_new_for_data from commit d18b59d9e6 so it wouldn't
compile.

Reviewed-by: Robert Bragg <12e9293ec6b30c7fa8a0926af42807e929c1684f@linux.intel.com>

Distrotech/cogl,djdeath/cogl,djdeath/cogl-android,gcampax/cogl,djdeath/cogl-android,Distrotech/cogl,djdeath/cogl-android,gcampax/cogl,djdeath/cogl,Distrotech/cogl,gcampax/cogl,Distrotech/cogl,gcampax/cogl,djdeath/cogl