Move SanitizerArgs to the clang Driver

Summary:
This change turns SanitizerArgs into high-level options
stored in the Driver, which are parsed lazily. This fixes an issue of multiple copies of the same diagnostic message produced by sanitizer arguments parser.

Reviewers: rsmith

Reviewed By: rsmith

CC: chandlerc, eugenis, cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1341

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188660 91177308-0d34-0410-b5e6-96231b3b80d8