pgsql: Upgrade to Autoconf 2.63 This upgrades the configure

Log Message:
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Upgrade to Autoconf 2.63

This upgrades the configure infrastructure to the latest Autoconf version.
Some notable news are:
- The workaround for the broken fseeko() test is gone.
- Checking for unknown options is now provided by Autoconf itself.
- Fixes for Mac OS X

Modified Files:
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pgsql:
configure (r1.645 -> r1.646)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure?r1=1.645&r2=1.646)
configure.in (r1.603 -> r1.604)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure.in?r1=1.603&r2=1.604)
pgsql/config:
c-library.m4 (r1.33 -> r1.34)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/config/c-library.m4?r1=1.33&r2=1.34)
general.m4 (r1.10 -> r1.11)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/config/general.m4?r1=1.10&r2=1.11)
pgsql/src/include:
pg_config.h.in (r1.139 -> r1.140)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/pg_config.h.in?r1=1.139&r2=1.140)