pgsql: Double-space commands in system_constraints.sql/system_functions

Double-space commands in system_constraints.sql/system_functions.sql.

Previously, any error reported by the backend while reading
system_constraints.sql would report the entire file, not just the
particular command it was working on. (Ask me how I know.) Likewise,
there were chunks of system_functions.sql that would be read as one
command, which would be annoying if anything failed there.

The issue for system_constraints.sql is an oversight in commit
dfb75e478. I didn't try to trace down where the poor formatting
in system_functions.sql started, but it's certainly contrary to
the advice at the head of that file.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7dde98728a2ef6d48ef397ee783dd130fdb34e6b

Modified Files
--------------
src/backend/catalog/genbki.pl | 3 +-
src/backend/catalog/system_functions.sql | 47 ++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+), 1 deletion(-)