mesa/main: define _NEW_xxx flags as unsigned shifts
mesa/main: define _NEW_xxx flags as unsigned shifts

Since 1 << 31 complains about undefined behaviour; the others are changed
only for consistency.

Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>
Reviewed-by: Michel Dänzer <242b79f0804cf52679d58f27ed754158c1323c75@amd.com>
Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler