pgsql: Replace calls of htonl()/ntohl() with pg_bswap.h for GSSAPI encr

Replace calls of htonl()/ntohl() with pg_bswap.h for GSSAPI encryption

The in-core equivalents can make use of built-in functions if the
compiler supports this option, making optimizations possible.  0ba99c8
replaced all existing calls in the code base at this time, but b0b39f7
(GSSAPI encryption) has forgotten to do the switch.

Discussion: https://postgr.es/m/20201014055303.GG3349@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/86dba33217bb0b48fcf59da76912c3382b4418cd

Modified Files
--------------
src/backend/libpq/be-secure-gssapi.c    | 8 ++++----
src/interfaces/libpq/fe-secure-gssapi.c | 8 ++++----
2 files changed, 8 insertions(+), 8 deletions(-)