[MIR] Print on the given output instead of stderr.

Currently the MIR framework prints all its outputs (errors and actual
representation) on stderr.

This patch fixes that by printing the regular output in the output
specified with -o.

Differential Revision: http://reviews.llvm.org/D22251

llvm-svn: 275314
GitOrigin-RevId: 545e558b8209d1467ce0249ed9b5c45e6c81e8c5
100 files changed