Fix sparc32 bits/long-double.h (bug 21987).

Fix sparc32 bits/long-double.h (bug 21987).

My refactoring of long double information

commit 0acb8a2a855395c25b1feef2470f4d7ca4bed589
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Wed Dec 14 18:27:56 2016 +0000

    Refactor long double information into bits/long-double.h.

resulted in sparc32 configurations installing the ldbl-opt version of
bits/long-double.h instead of the intended
sysdeps/unix/sysv/linux/sparc version.

For sparc32 by itself, this is not a problem, since the ldbl-opt
version is correct for sparc32.  However, both sparc32 and sparc64 are
supposed to install sets of headers that work for both of them, so
that a single sysroot, whichever order the libraries are built and
installed in, works for both.  The effect of having the wrong version
installed is that you end up with a miscompiled sparc64 libstdc++
which fails glibc's configure tests for the C++ compiler.

This patch moves the header from sysdeps/unix/sysv/linux/sparc to
separate copies of the same file for sparc32 and sparc64, to ensure it
comes before ldbl-opt in the sysdeps directory ordering.

Tested with build-many-glibcs.py for sparc64-linux-gnu and
sparcv9-linux-gnu.

	[BZ #21987]
	* sysdeps/unix/sysv/linux/sparc/bits/long-double.h: Remove file
	and copy to ...
	* sysdeps/unix/sysv/linux/sparc/sparc32/bits/long-double.h:
	... here.
	* sysdeps/unix/sysv/linux/sparc/sparc64/bits/long-double.h:
	... and here.