acinclude.m4 (LIB_AC_PROG_CXX): Remove CXX from the list of alternatives for CXX_libstdcxx, now that it is useless.

* acinclude.m4 (LIB_AC_PROG_CXX): Remove CXX from the list of
alternatives for CXX_libstdcxx, now that it is useless.
* aclocal.m4, configure: Rebuilt.

From-SVN: r37283