Fix cross-Linux libstdc++ configuration issues

[Benjamin Kosnik]

> 2008-06-06  Joseph Myers  <joseph@codesourcery.com>
> 
> 	* configure.ac: Do not check for gconv.h.
> 	* crossconfig.m4 (GLIBCXX_CROSSCONFIG): Do not test for
> gconv.h or gconf.h.  For glibc and uClibc systems, define
> 	_GLIBCXX_USE_RANDOM_TR1 and HAVE_MMAP and use AC_LC_MESSAGES
> and AM_ICONV.
> 	* configure, config.h.in: Regenerate.

OK

-benjamin