Holds placement avoid calling non-existent func.

Holds placement avoid calling non-existent func.

Avoid calling an undefined function during hold placement.  In older
versions of opensrf, this kind of the thing would silently fail.  (Well,
it would log to the stderr file).  Modern opensrf allows Perl the throw
a standard exception, which stops execution.

Signed-off-by: Bill Erickson <berickxx@gmail.com>