initialize pthread mutexes to avoid compiler common variable stupidity

initialize pthread mutexes to avoid compiler common variable stupidity

instead of worrying about ranlib versus ranlib -c, -fno-common, etc,
just initialize the variables if an initializer exists

Change-Id: I6ed28df4d2134f84359a1bc55706e75d54e6e083
Reviewed-on: http://gerrit.openafs.org/1166
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>