* aclocal.m4 (AC_GCC_C_LONG_DOUBLE): New macro.

        * configure.in (AC_GCC_C_LONG_DOUBLE): Call it.

        * gansidecl.h (HAVE_LONG_DOUBLE): Define if gcc for stage2.

        * ggc-simple.c (HAVE_LONG_DOUBLE): Test before using long double.

From-SVN: r29432