Fix translation domain in pg_basebackup

For some reason, we've been overlooking the fact that pg_receivexlog
and pg_recvlogical are using wrong translation domains all along,
so their output hasn't ever been translated.  The right domain is
pg_basebackup, not their own executable names.

Noticed by Ioseph Kim, who's been working on the Korean translation.

Backpatch pg_receivexlog to 9.2 and pg_recvlogical to 9.4.