Relocatable locale

Magnus found out that LOCALEDIR wasn't being handled in a relocatable
manner.

This patch fixes that. It also adjusts the get_*_path functions to
limit values to MAXPGPATH.

I have two questions. First, setlocale() seemed to be inconsistently
set inside and outside of ENABLE_NLS. I assume the proper location is
inside. Second, libpq has a locale setting for error messages, but a
libpq program could be in any directory, so I see no way to make that
relocatable. Instead, I just use the hardcoded path. I could make it
relocatable, but that seems to error-prone, plus I would have to look up
the exec path and stuff, and it seemed too complicated.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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