Support for PowerPC uClibc with 128-bit long double

[Benjamin Kosnik]

> libstdc++-v3:
> 2007-04-17  Joseph Myers  <joseph@codesourcery.com>
> 
> 	* configure.ac: Allow both powerpc*-*-linux* and powerpc*-*-gnu*
> 	for long double compatibility.
> 	* configure: Regenerate.
> 	* src/complex_io.cc, src/istream-inst.cc, src/ostream-inst.cc:
> 	Condition some _GLIBCXX_LDBL_COMPAT calls on _GLIBCXX_USE_WCHAR_T.

This part looks fine.

-benjamin