Summary:
Adds strnlen to the common interceptors, under the existing flag
intercept_strlen.
Removes the now-duplicate strnlen interceptor from asan and msan.
This adds strnlen to tsan, which previously did not intercept it.
Adds a new test of strnlen to the sanitizer_common test cases.
Reviewers: samsonov
Subscribers: zhaoqin, llvm-commits, kcc
Differential Revision: http://reviews.llvm.org/D18397
llvm-svn: 264195