Add -funique-section-names and -fno-unique-section-names options.

For now -funique-section-names is the default, so no change in default behavior.

The total .o size in a build of llvm and clang goes from 241687775 to 230649031
bytes if -fno-unique-section-names is used.

llvm-svn: 230031
GitOrigin-RevId: 6b07a1c6ee50dcf4d52a4a314b4774347f9b22c0
7 files changed