-if [ -f ${if_topsrcdir}/libstdc++/Makefile.in ]; then
-# We check libstdc++ for libstdcxx_interface.
-libstdcxx_interface=`grep "^INTERFACE" ${if_topsrcdir}/libstdc++/Makefile.in | sed 's/INTERFACE[ ]*=[ ]*\(.*\)/\1/'`
-else
-libstdcxx_interface=
-fi
-
-if [ -f ${if_topsrcdir}/gcc/cp/Makefile.in ]; then
-# We check gcc/cp for cxx_interface.
-cxx_interface=`grep "^INTERFACE" ${if_topsrcdir}/gcc/cp/Makefile.in | sed 's/INTERFACE[ ]*=[ ]*\(.*\)/\1/'`
-else
-cxx_interface=
+# Set libstdcxx_incdir.
+# This is the same as gcc/configure.in and libstdc++-v3/acinclude.m4.
+if test -z "$gcc_version"; then
+ if test -z "${gcc_version_trigger}" \
+ && test -f ${if_topsrcdir}/gcc/version.c; then
+ gcc_version_trigger=${if_topsrcdir}/gcc/version.c
+ fi
+ if test -f "${gcc_version_trigger}"; then
+ gcc_version_full=`grep version_string "${gcc_version_trigger}" | sed -e 's/.*"\([^"]*\)".*/\1/'`
+ else
+ gcc_version_full=`$CC -v 2>&1 | sed -n 's/^gcc version //p'`
+ fi
+ gcc_version=`echo ${gcc_version_full} | sed -e 's/\([^ ]*\) .*/\1/'`