pgsql: Make ecpg's rjulmdy() and rmdyjul() agree with their declaration

Make ecpg's rjulmdy() and rmdyjul() agree with their declarations.

We had "short *mdy" in the extern declarations, but "short mdy[3]"
in the actual function definitions. Per C99 these are equivalent,
but recent versions of gcc have started to issue warnings about
the inconsistency. Clean it up before the warnings get any more
widespread.

Back-patch, in case anyone wants to build older PG versions with
bleeding-edge compilers.

Discussion: /messages/by-id/2401575.1611764534@sss.pgh.pa.us

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/1449770d31fd684a078865334a3a155a7ee534ae

Modified Files
--------------
src/interfaces/ecpg/compatlib/informix.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)