Several LLVM tools write text files/streams without using OF_Text.
This can cause problems on platforms which distinguish between
text and binary output. This PR adds the OF_Text flag for the
following tools:
- llvm-dis
- llvm-dwarfdump
- llvm-mca
- llvm-mc (assembler files only)
- opt (assembler files only)
- RemarkStreamer (used e.g. by opt)
Most notably, llc already makes the distinction between text and binary output.
Depending on RemarksFormat, the output can also be LLVM Bitstream. Should this set OF_Text only if the format is YAML?