Create SCMUTEX_INITIALIZER to abstract out PTHREAD_MUTEX_INITIALIZER

This allows replacing pthread mutexes with other types of mutex.
Merge multiple copies of CreateTimeString() to one copy.

There were 8 identical copies of CreateTimeString() in 8 files.
Most used SCLocalTime, to replace localtime_r(), but some did not.
Created one copy in util-time.c.
Merge pull request #6 from ken-tilera/mutex-init

Mutex init
Merge pull request #7 from ken-tilera/create-time

Create time