As a bare minimum we want to ensure that are releases are able to build
with support for gles1, gles2, gl, egl and glx. Previously we only
checked the build with gl + glx enabled and our last release actually
missed a header file required for building with egl.
The recommended command to check for differences from master to the
remote master was using git log with a range from the local master to
the remote master but this wouldn't work if the local master is ahead
of the remote master because the range is backwards. This patch
changes it to recommend git diff --stat instead because then the
command would work even if the two branches have diverged.
