Sync timezone code with upstream release tzcode2016c

Well, that was just about as tedious as I feared it might be, but
attached is a patch for $SUBJECT. We should apply this, and
probably eventually back-patch it, but it'd be wise to let it
age awhile in HEAD first. Is anyone interested in reviewing it,
or shall I just push it and see what the buildfarm thinks?

A note about comparing this to upstream: I found that the best
way to do that was to run the IANA source files through a sed
filter like this:

sed -r \
-e 's/^([ ]*)\*\*([ ])/\1 *\2/' \
-e 's/^([ ]*)\*\*$/\1 */' \
-e 's|^\*/| */|' \
-e 's/register //g' \
-e 's/int_fast32_t/int32/g' \
-e 's/int_fast64_t/int64/g' \
-e 's/struct tm\b/struct pg_tm/g' \
-e 's/\btime_t\b/pg_time_t/g' \

and then pgindent them. (If you pgindent without this, it'll make
a hash of their preferred block-comment format with double **'s.
As long as I had to do that, I figured I could make the filter
deal with substituting typedef names and getting rid of their
overenthusiasm for "register".)

regards, tom lane