glAttributes also include `gl_` names. These don't have a location and
should be ignored during shader interface creation. Those internal names
received a location of -1 and therefore the bitmasking was undefined.
Users wouldn't notice this, but ASAN warned developers of this situation.
ASAN could quit making ASAN un-usable as most shaders have this issue.
Reviewed By: Clément Foucault`
Differential Revision: https://developer.blender.org/D7448
d34c5eec19