IRIX: Implement makesname()

IRIX: Implement makesname()

makesname() make a semaphore name for use in <sys/sema.h>-type routines on
IRIX.  It takes as input a pointer to an allocated string buffer (sname) of
size METER_NAMSZ, a string prefix (prefix), and a vnode number (v_number).
When complete, sname is returned, pointing to the beginning of a
NULL-terminated string containing the new name, with a maximum of
(METER_NAMSZ-1) characters plus the NULL.  The name is a concatenation of
the string at 'prefix' and the ASCII representation of the number in
'v_number'.

Note: Due to IRIX's use of uint64 to represent vnumber_t and a maximum
semaphore name length of 15 (METER_NAMSZ-1), this function cannot be
guaranteed to produce a name which uniquely describes a vnode.

makesname() is already called from afs_vcache.c but not (or no longer)
available / implemented elsewhere.

Change-Id: I4331c161b68b39a4c067691c97363b637d13ff15
Change-Id: Ia0a615426dc05e01a98e53e89ec3bae3726cac34
Reviewed-on: http://gerrit.openafs.org/2155
Reviewed-by: Chaz Chandler <clc31@inbox.com>
Tested-by: Chaz Chandler <clc31@inbox.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>