Android: enable building on arm64
Android: enable building on arm64

Use the LOCAL_CFLAGS_{32/64} instead of arch specific variants to define
the DEFAULT_DRIVER_DIR. This enables building for arm64.

Cc: Chih-Wei Huang <168fbe9b48536378ad61dccedb637b5a226976e8@android-x86.org>
Signed-off-by: Rob Herring <fbb37eacae100e13076d5c4b46f06cfa4d6fa9f8@kernel.org>
Reviewed-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler