* clutter/cogl/gles/cogl-fbo.c: Copy the code from gl/cogl-fbo but
use the API calls directly instead of loading an extension because
it is part of the core in GLES 2.
* clutter/cogl/gles/cogl.c (_cogl_features_init): Report
COGL_FEATURE_OFFSCREEN.
* clutter/cogl/gles/cogl-fbo.h (CoglFbo): Add gl_stencil_handle.
* clutter/cogl/gles/cogl-context.h (CoglContext): Add
viewport_store
* tests/test-fbo.c (make_shader): Conditionally use the GLES 2
names of the shader variables
