pgsql: Fix assorted minor bogosity in GSSAPI transport error messages.

Fix assorted minor bogosity in GSSAPI transport error messages.

I noted that some buildfarm members were complaining about %ld being
used to format values that are (probably) declared size_t. Use %zu
instead, and insert a cast just in case some versions of the GSSAPI
API declare the length field differently. While at it, clean up
gratuitous differences in wording of equivalent messages, show
the complained-of length in all relevant messages not just some,
include trailing newline where needed, adjust random deviations
from project-standard code layout and message style, etc.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8cde7f49483d7e21569f61108fc80a8fe9e83e56

Modified Files
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src/backend/libpq/be-secure-gssapi.c | 27 ++++++++++++++++++---------
src/interfaces/libpq/fe-secure-gssapi.c | 24 +++++++++++++-----------
2 files changed, 31 insertions(+), 20 deletions(-)