[clang-tidy] Enhance misc-suspicious-string-compare to move down false-positives.

Summary:
The checker was noisy when running over llvm code base.
This patch is impriving the way string-compare functions are matched.

1) By default, do not report !strcmp(...) unless it's activate by the user,
2) Only match suspicious expression over a subset of expression (binary operator),
3) Added matching of macro wrapper used with clang on linux.

See bug: 27465.

Reviewers: alexfh

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D19497

llvm-svn: 267570