[libsanitizer] StopTheWorld in sanitizer_common

StopTheWorld puts the process in a suspended state before running the
user-supplied callback. To be used in TSan and in leak checking code.

Linux implementation provided.

Patch by Sergey Matveev (earthdok@google.com)


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@177156 91177308-0d34-0410-b5e6-96231b3b80d8