[sanitizer] fix gcc build warnings

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@177149 91177308-0d34-0410-b5e6-96231b3b80d8
[Sanitizer] Don't link tests with -lpthread on Android.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@177151 91177308-0d34-0410-b5e6-96231b3b80d8