[pgpool-committers: 4675] pgpool: Prevent pcp_recovery_node from recovering "unused" status node.

[Tatsuo Ishii]

Prevent pcp_recovery_node from recovering "unused" status node.

This allowed to try to recover a node without configuration data,
which leads to variety of problems. See discussion:
https://www.pgpool.net/pipermail/pgpool-general/2018-March/006021.html
for more details.

Also I fixed pgpool_recovery function so that it quotes an empty
string argument with double quotes. Without this, the argument is
treated as if it does not exist, which was the source of the complain
from the user.

Branch
------
V3_5_STABLE

Details
-------
https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=7f47596405d326c4cd493e1b112aeaf993d5a8f9

Modified Files
--------------
src/pcp_con/recovery.c                    | 4 ++++
src/sql/pgpool-recovery/pgpool-recovery.c | 6 +++---
2 files changed, 7 insertions(+), 3 deletions(-)