ECPG timestamp '%j'

Michael,

While looking at complaints from the Coverity scanner system, it looks
like it's detected a case in ECPG where we provide a "day-of-year"
format option (%j), but we never actually calculate what the day of
year *is*, resulting in an uninitialized value.

Other parts of the code (non-ECPG) appears to realize that timestamp2tm
doesn't fill in day-of-year in the struct and they calculate it
afterwards. Perhaps ECPG needs to adopt that approach also, perhaps
either in dttofmtasc_replace() or PGTYPEStimestamp_fmt_asc()..?

I was able to get what I believe is an incorrect result through a bit
of hacking on the ECPG test cases:

timestamp_fmt_asc: 0: 10922-abc%

after adding:

out = (char*) malloc(32);
i = PGTYPEStimestamp_fmt_asc(&ts1, out, 31, "%j-abc%%");
printf("timestamp_fmt_asc: %d: %s\n", i, out);
free(out);

into pgtypeslib/dt_test.pgc.

If you don't have time to look into this, let me know and I'll try and
get back to it soon.

Thanks!

Stephen