tsan: allows to suppress races on global variables


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@183672 91177308-0d34-0410-b5e6-96231b3b80d8
tsan: add system tests for suppressions


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@183673 91177308-0d34-0410-b5e6-96231b3b80d8