android: always set __STDC_*_MACROS for C++ sources
android: always set __STDC_*_MACROS for C++ sources

Various parts of the code depend on the macros being defined.

Just set those unconditionally, only where needed (c++ sources) so that
we can drop the workarounds through the code.

Cc: Rob Herring <fbb37eacae100e13076d5c4b46f06cfa4d6fa9f8@kernel.org>
Cc: Chih-Wei Huang <168fbe9b48536378ad61dccedb637b5a226976e8@android-x86.org>
Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>
Reviewed-by: Eric Engestrom <de0b63cf2dfb1fae8ed3c3b4244856a05677d4f0@imgtec.com>
Reviewed-by: Jose Fonseca <61b5a29db2c0650f7c8510f93eece059c1b09320@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler