glsl: copy how_declared when lowering interface blocks
glsl: copy how_declared when lowering interface blocks

Cc: Gregory Hainaut <874ed946d2e42378b22d113f3a5c5d90141d0a46@gmail.com>
Reviewed-by: Tapani Pälli <cdcb67a5e49297de94340ca09f25994bd5e7f762@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler