Fix Coverity warnings regarding r293229

rpcbind/check_bound.c
Fix CID1347798, a memory leak in mergeaddr.

rpcbind/tests/addrmerge_test.c
Fix CID1347800 through CID1347803, memory leaks in ATF tests. They
are harmless because each ATF test case runs in its own process, but
they are trivial to fix. Fix a few other leaks that Coverity didn't
detect, too.

Coverity CID: 1347798, 1347800, 1347801, 1347802, 1347803
MFC after: 2 weeks
X-MFC-With: 293229
Sponsored by: Spectra Logic Corp