Further encapsulate Ceres's Mutex class.

There are cases where one wishes to link Ceres against another
application or library which uses a mutex implementation with
similar ancestry to the one in Ceres. In those cases there are
problems due to macro interactions which can't be contained with
namespaces.

This further isolates the Ceres Mutex class by adding CERES_
prefix to all the macros and also working around a macro name
clash with MutexLock by renaming the MutexLock class to
CeresMutexLock.

Change-Id: I923f4427d5939823ea67d48005a90391736d7751
4 files changed