mesa/main: fix validation of GL_ANY_SAMPLES_PASSED

mesa/main: fix validation of GL_ANY_SAMPLES_PASSED

ctx->Extensions.ARB_occlusion_query2 is set based on the driver-
capabilities, not based on the context type. We need to check against
_mesa_has_ARB_occlusion_query2(ctx) instead to figure out if the
extension is really supported.

In addition, EXT_occlusion_query_boolean should also allow this
behavior.

This shouldn't cause any functional change, as all drivers that support
ARB_occlusion_query2 should in practice enable either
ARB_occlusion_query2 or EXT_occlusion_query_boolean under all APIs that
export this symbol.

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>