RFR (S) 8198760: Move global lock SpaceManager::_expand_lock to MutexLocker.cpp

[coleen.phillimore at oracle.com]

Summary: We should avoid having global locks buried in cpp files

open webrev at http://cr.openjdk.java.net/~coleenp/8198760.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8198760

Tested with mach5 tier1 and 2.

Thanks,
Coleen