dnl Usage: TL_AC_GXX_INCLUDE_DIRdnldnl Set $gxx_include_dir to the location of the installed C++ includednl directory. The value depends on $gcc_version and the configurationdnl options --with-gxx-include-dir and --enable-version-specific-runtime-libs.dnldnl If you change the default here, you'll need to change the gcc anddnl libstdc++-v3 subdirectories too.AC_DEFUN([TL_AC_GXX_INCLUDE_DIR],[case "${with_gxx_include_dir}" inyes)AC_MSG_ERROR([--with-gxx-include-dir=[[dir]] requires a directory]);;no | "")case "${enable_version_specific_runtime_libs}" inyes) gxx_include_dir='$(libsubdir)/include/c++' ;;*)libstdcxx_incdir='c++/$(gcc_version)'gxx_include_dir='$(prefix)/include/$(libstdcxx_incdir)' ;;esac ;;*) gxx_include_dir=${with_gxx_include_dir} ;;esacAC_SUBST(gxx_include_dir)AC_SUBST(libstdcxx_incdir)])