Backed out rev.1.10. It tried to implement ldexpf() as a weak reference

Backed out rev.1.10.  It tried to implement ldexpf() as a weak reference
to scalbf(), but ldexpf() cannot be implemented in that way since the
types of the second parameter differ.  ldexpf() can be implemented as
a weak or strong reference to scalbnf() (*) but that was already done
long before rev.1.10 was committed.  The old implementation uses a
reference, so rev.1.10 had no effect on applications.  The C files for
the scalb() family are not used for amd64 or i386, so rev.1.10 had even
less effect for these arches.

(*) scalbnf() raises the radix to the given exponent, while ldexpf()
raises 2 to the given exponent.  Thus the functions are equivalent
except possibly for their error handling iff the radix is 2.  Standards
more or less require identical error handling.  Under FreeBSD, the
functions are equivalent except for more details being missing in
scalbnf()'s man page.