ia64: math: add __scalbn* aliases

ia64: math: add __scalbn* aliases

All other ports have __scalbn* aliases pointing back to scalbn*, but
the ia64 code had omitted them.  This didn't really matter as none
of the common code called them, but after a recent update, that's no
longer true.  Add the aliases needed by some common code to fix link
errors with libm due to them missing.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>