Remove redundant ldbl-64-128 files.

Various source files in ldbl-64-128 are redundant, because they wrap
files that no longer provide public symbols that need special
versioning (those symbols having moved to separate errno-setting
wrappers), or, in the case of w_scalblnl.c, because the type-generic
template now does everything required (it deals with symbol versioning
for use in libm, and this file is never built for libc anyway - the
compat scalbln* symbols in libc, as opposed to scalbn*, are only for
i386 and m68k and are aliases to the corresponding scalbn* symbols).
This patch removes those redundant files.

Tested with build-many-glibcs.py (for all ldbl-64-128 configurations)
that installed stripped shared libraries are unchanged by this patch.

	* sysdeps/ieee754/ldbl-64-128/e_ilogbl.c: Remove file.
	* sysdeps/ieee754/ldbl-64-128/s_log1pl.c: Likewise.
	* sysdeps/ieee754/ldbl-64-128/s_scalblnl.c: Likewise.
	* sysdeps/ieee754/ldbl-64-128/s_scalbnl.c: Likewise.
	* sysdeps/ieee754/ldbl-64-128/w_scalblnl.c: Likewise.