Add preprocessor "defined" operator corner cases
The GLES3 shader tests have already required "defined" operator generated
by macro replacement to work. This is not specified by the C++ standard,
and has some corner cases where implementations might differ. Test the
corner cases to ensure fully compatible implementations.
These cases were already tested against some existing implementations on
Nexus devices, and the implementations mostly passed.
Change-Id: Ic54afc9436bb2ad2d7bfc7dc1e1833f700d3ca49