orafce - orafce: Optimize decode() by caching equality operator

Log Message:
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Optimize decode() by caching equality operator functions and add a special version for bpchar type.

Modified Files:
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orafce:
orafunc.sql.in (r1.48 -> r1.49)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/orafunc.sql.in.diff?r1=1.48&r2=1.49)
others.c (r1.12 -> r1.13)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/others.c.diff?r1=1.12&r2=1.13)