dnl *** X11 interface compilation ***
build_against_x11="no"
if test "x$bc_with_x11" != "xno" ; then
    # XXX ugly hack (that needs to die)
    X_PREFIX=/usr/X11R6
    if test "x$bc_with_x11_val" != "x" ; then
        X_PREFIX="$bc_with_x11_val"
    fi
    X_CFLAGS="-I${X_PREFIX}/include"
    X_LIBS="-L${X_PREFIX}/lib $LIBX11 $LIBXI"

    x11_works=no
    AC_MSG_CHECKING(for X11 header functionality)
    PRELDFLAGS="$LDFLAGS"
    LDFLAGS="$LDFLAGS $X_LIBS"
    AC_TRY_RUN([