r600g: remove duplicate memset by using a pointer, and constify args
r600g: remove duplicate memset by using a pointer, and constify args

Signed-off-by: Constantine Kharlamov <e03bce329c16901cc8bd6d578788b9e37d0f64fd@yandex.ru>
Signed-off-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>
Tested-by: Dieter Nützel <902ea9f4f1fbe947e8e8c77ca59f21dfca158b7e@nuetzel-hh.de>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler