[tsan] Allow memmove interceptor to be used when TSan is not initialized

A call to memmove is used early during new thread initialization on OS X. This patch uses the `COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED` check, similarly to how we deal with other early-used interceptors.

Differential Revision: http://reviews.llvm.org/D14377

llvm-svn: 252161