[InstCombine] Adding "\n" to debug output. NFC.

Summary:
[InstCombine] Adding '\n' to debug output. NFC.

Patch by Zhaoshi Zheng <zhaoshiz@codeaurora.org>

Reviewers: apazos, majnemer, weimingz

Subscribers: arsenm, llvm-commits

Differential Revision: http://reviews.llvm.org/D15403

llvm-svn: 255920