pipeline: tidy up definition of *END defines
pipeline: tidy up definition of *END defines

There is some fairly awkward #ifdefing to determine which vertends,
fragends and progends are available at build time. This patch
consolidates the #ifdefing of vertend, fragend and progend defines to
make for slightly easier reading.

Reviewed-by: Neil Roberts <neil@linux.intel.com>

(cherry picked from commit 098d6244bf7c8f2a4ca24206c6e8271d589ed4c9)

Distrotech/cogl,Distrotech/cogl,Distrotech/cogl,Distrotech/cogl