misc

Hi, here are patches I promised (against 6.3.2):

* character_length(), position(), substring() are now aware of
          multi-byte characters
* add octet_length()
* add --with-mb option to configure
* new regression tests for EUC_KR
  (contributed by "Soonmyung. Hong" <hong@lunaris.hanmesoft.co.kr>)
* add some test cases to the EUC_JP regression test
* fix problem in regress/regress.sh in case of System V
* fix toupper(), tolower() to handle 8bit chars

note that:

o  patches for both configure.in and configure are
included. maybe the one for configure is not necessary.

o pg_proc.h was modified to add octet_length(). I used OIDs
(1374-1379) for that. Please let me know if these numbers are not
appropriate.