Adjust pg_dumpall so that it emits ENCODING, LC_COLLATE, and LC_CTYPE options

Adjust pg_dumpall so that it emits ENCODING, LC_COLLATE, and LC_CTYPE options
in its CREATE DATABASE commands only for databases that have settings
different from the installation defaults.  This is a low-tech method of
avoiding unnecessary platform dependencies in dump files.  Eventually we ought
to have a platform-independent way of specifying LC_COLLATE and LC_CTYPE, but
that's not going to happen for 8.4, and this patch at least avoids the issue
for people who aren't setting up per-database locales.  ENCODING doesn't have
the platform dependency problem, but it seems consistent to make it act the
same as the locale settings.