[sanitizer] Move the PTHREAD_DESTRUCTOR_ITERATIONS constant to sanitizer_linux.h.

Add a test.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@192442 91177308-0d34-0410-b5e6-96231b3b80d8
[sanitizer] Ninja style fix to r192442.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@192443 91177308-0d34-0410-b5e6-96231b3b80d8