Fold together the two implementations of 6.7.3p2 in SemaType. Fix two bugs,...

Fold together the two implementations of 6.7.3p2 in SemaType. Fix two bugs, each of which was only present in one version:
 * Give the right diagnostic for 'restrict' applied to a non-pointer, non-reference type.
 * Don't reject 'restrict' applied indirectly to an Objective-C object pointer type (eg, through template instantiation).

llvm-svn: 178200