Add -DTHREAD_SANITIZER for TS builds

This allows for defining other macros under the builds used
by the thread sanitizer (like undefining the ntoh-macros
causing compiler warnings on our ts builder)

Change-Id: Ic44184ef69e5be4fc2ee9c788c8ffbfc7fbf099c
Reviewed-on: http://review.couchbase.org/55385
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: buildbot <build@couchbase.com>

cmake/Modules/CouchbaseThreadSanitizer.cmake

@@ -29,6 +29,8 @@ IF (CB_THREADSANITIZER)
         # Configure CTest's MemCheck to ThreadSanitizer.
         SET(MEMORYCHECK_TYPE ThreadSanitizer)
 
+        ADD_DEFINITIONS(-DTHREAD_SANITIZER)
+
         # Override the normal ADD_TEST macro to set the TSAN_OPTIONS
         # environment variable - this allows us to specify the
         # suppressions file to use.