pgpool: Fix response buffer pointer advancement in do_error_execute_com

Fix response buffer pointer advancement in do_error_execute_command

The response body is copied len bytes, but the buffer pointer was
advanced by sizeof(len). When a zero-length response body was received,
the pointer advanced by four bytes even though no body was copied,
causing subsequent saved responses to be corrupted.

Advance the pointer by len in both protocol v2 and v3 paths.

Author: Taiki Koshino <koshino(at)srasoss(dot)co(dot)jp>
Discussion: https://www.postgresql.org/message-id/OS9P286MB6486821B656397FBCD72BE5394BF2%40OS9P286MB6486.JPNP286.PROD.OUTLOOK.COM
Backpatch-through: v4.3

Branch
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V4_6_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=2da451f98934e749a3b791664654acb3ace67041

Modified Files
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src/protocol/pool_process_query.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)