Don't create a (empty) output file, and don't warn about bitcode output

Don't create a (empty) output file, and don't warn about bitcode output
to a console, when --analyze is used.

Similarly, avoid creating an empty output file when --disable-output is used.

Print a warning when the -o option appears with either --analyze or
--disable-output, to indicate that the option is being ignored.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93685 91177308-0d34-0410-b5e6-96231b3b80d8