i965: move brw_define.h ifndef guard to the top
i965: move brw_define.h ifndef guard to the top

Cc: 59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org
Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>
Reviewed-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler