Change the asmprinter to print the comment character before the

Change the asmprinter to print the comment character before the
"inlineasmstart/end" strings so that the contents of the directive
are separate from the comment character.  This lets elf targets
get #APP/#NOAPP for free even if they don't use "#" as the comment
character.  This also allows hoisting the darwin stuff up to the
shared TAI class.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78737 91177308-0d34-0410-b5e6-96231b3b80d8