Make the arbitrary section name be something mach-o compatible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203972 91177308-0d34-0410-b5e6-96231b3b80d8
Remove command line option for CU hashing. This is on by default now.
Fix up testcases and use of flag.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203973 91177308-0d34-0410-b5e6-96231b3b80d8