radeonsi: Set PIPE_SHADER_CAP_MAX_SHADER_IMAGES
radeonsi: Set PIPE_SHADER_CAP_MAX_SHADER_IMAGES

This enables ARB_shader_image_load_store and ARB_shader_image_size.

Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
[allow the same number of images for all shader stages and require LLVM 3.9]

Reviewed-by: Marek Olšák <8c7344a1abdb103e79ecfd488098373070c3c70e@amd.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler