[SemaObjC] Properly handle mix between type arguments and protocols.

Under certain conditions clang currently fails to properly diagnostic ObjectC
parameter list when type args and protocols are mixed in the same list. This
happens when the first item in the parameter list is a (1) protocol, (2)
unknown type or (3) a list of protocols/unknown types up to the first type
argument. Fix the problem to report the proper error, example:

NSArray<M, NSValue *, NSURL, NSArray <id <M>>> *foo = @[@"a"];
NSNumber *bar = foo[0];
NSLog(@"%@", bar);

$ clang ...
x.m:7:13: error: angle brackets contain both a type ('NSValue') and a protocol ('M')
        NSArray<M, NSValue *, NSURL, NSArray <id <M>>> *foo = @[@"a"];
                ~  ^

Differential Revision: http://reviews.llvm.org/D18997

rdar://problem/22204367

llvm-svn: 266245