The following patch allowed me to proceed for c,c++,lto,fortran,ada,objc,obj-c++ up to libada which has the same problem:
--- ../_clean/gcc/configure 2012-12-20 17:19:54.000000000 +0100 +++ ../p_work/gcc/configure 2012-12-21 23:44:46.000000000 +0100 @@ -10321,9 +10321,9 @@ $as_echo "#define HAVE_LANGINFO_CODESET # We will need to find libiberty.h and ansidecl.h saved_CFLAGS="$CFLAGS" -CFLAGS="$CFLAGS -I${srcdir} -I${srcdir}/../include" +CFLAGS="$CFLAGS -I${srcdir} -I${srcdir}/../include $GMPINC" saved_CXXFLAGS="$CXXFLAGS" -CXXFLAGS="$CXXFLAGS -I${srcdir} -I${srcdir}/../include" +CXXFLAGS="$CXXFLAGS -I${srcdir} -I${srcdir}/../include $GMPINC" for ac_func in getenv atol asprintf sbrk abort atof getcwd getwd \ strsignal strstr stpcpy strverscmp \ errno snprintf vsnprintf vasprintf malloc realloc calloc \ Dominique