python - be: Add and use interface to deleting function cache entries.

Log Message:
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Add and use interface to deleting function cache entries.

Use this in the validator to be sure to grab the new function the next time
around. While a more appropriate solution would handle the general case that the
function cache exists in, this is useful as it will be sure to keep some 0.3
testing pains absent in future versions.

Modified Files:
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be/include/pypg:
cis.h (r1.9 -> r1.10)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/include/pypg/cis.h.diff?r1=1.9&r2=1.10)
function.h (r1.5 -> r1.6)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/include/pypg/function.h.diff?r1=1.5&r2=1.6)
be/src:
function.c (r1.19 -> r1.20)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/function.c.diff?r1=1.19&r2=1.20)
module.c (r1.25 -> r1.26)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/module.c.diff?r1=1.25&r2=1.26)
pl.c (r1.34 -> r1.35)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/pl.c.diff?r1=1.34&r2=1.35)