[fedfs-utils] fix a few coverity-spotted problems, v2

[Jim Meyering]

Per request I've adjusted the commit logs:
  - added Signed-off-by lines
  - added "spotted by coverity" where appropriate
I corrected 2/8 per your suggestion,
and I've identified the commit that introduced the bug fixed by 4/8.

[PATCH v2 1/8] mount: avoid two-byte heap write overrun
[PATCH v2 2/8] fedfsd: don't return freed memory through **pathname
[PATCH v2 3/8] build: avoid automake warnings about AM_PROG_AR
[PATCH v2 4/8] mount: don't make -s (sloppy) imply -v (verbose)
[PATCH v2 5/8] mount: don't leak upon LDAP parse failure
[PATCH v2 6/8] nsdb: don't leak a read buffer upon certfile open
[PATCH v2 7/8] libsi: don't leak a struct srvinfo upon failed strdup
[PATCH v2 8/8] fedfsd: don't double-free upon ENOMEM