Add more test cases for 'objc_protocol_requires_explicit_implementation'.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197128 91177308-0d34-0410-b5e6-96231b3b80d8
c-arcmt-test/Makefile: Fixup for LDFLAGS=-static on cygming, corresponding to r197116.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@197129 91177308-0d34-0410-b5e6-96231b3b80d8