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_4_STABLE

Details
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https://git.postgresql.org/gitweb?p=pgpool2.git;a=commitdiff;h=4b6b592e54b2d67b8944b66e9f4216732fe03126

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