[Loop Peeling] Introduce an option for profile based peeling disabling.

[Loop Peeling] Introduce an option for profile based peeling disabling.

This patch adds an ability to disable profile based peeling
causing the peeling of all iterations and as a result prohibits
further unroll/peeling attempts on that loop.

The motivation to get an ability to separate peeling usage in
pipeline where in the first part we peel only separate iterations if needed
and later in pipeline we apply the full peeling which will prohibit further peeling.

Reviewers: reames, fhahn
Reviewed By: reames
Subscribers: hiraditya, zzheng, dmgreen, llvm-commits
Differential Revision: https://reviews.llvm.org/D64983

llvm-svn: 367668