Remove the PreserveSource linker mode.
I noticed that it was untested, and forcing it on caused some tests to fail:
LLVM :: Linker/metadata-a.ll
LLVM :: Linker/prefixdata.ll
LLVM :: Linker/type-unique-odr-a.ll
LLVM :: Linker/type-unique-simple-a.ll
LLVM :: Linker/type-unique-simple2-a.ll
LLVM :: Linker/type-unique-simple2.ll
LLVM :: Linker/type-unique-type-array-a.ll
LLVM :: Linker/unnamed-addr1-a.ll
LLVM :: Linker/visibility1.ll
If it is to be resurrected, it has to be fixed and we should probably have a
-preserve-source command line option in llvm-mc and run tests with and without
it.
llvm-svn: 220741