Add ./configure --with flags for X11

--with-x11
--with-xt
--with-xaw

All disabled by default, since the code has probably bitrotted.

configure.ac

@@ -26,6 +26,24 @@ AC_TYPE_SIZE_T
 # Check whether we are doing a native build
 AM_CONDITIONAL(NATIVE_BUILD, test "${cross_compiling}" = "no")
 
+AC_ARG_WITH([x11],
+            [AS_HELP_STRING([--with-x11],
+              [enable support for libx11])],
+            [],
+            [with_x11=no])
+
+AC_ARG_WITH([xt],
+            [AS_HELP_STRING([--with-xt],
+              [enable support for libxt])],
+            [],
+            [with_xt=no])
+
+AC_ARG_WITH([xaw],
+            [AS_HELP_STRING([--with-xaw],
+              [enable support for libxaw])],
+            [],
+            [with_xaw=no])
+
 AC_CHECK_HEADERS(inttypes.h,
   [STDINT_HEADER="<inttypes.h>"],
   [AC_CHECK_HEADERS(sys/inttypes.h,
@@ -484,18 +502,22 @@ AC_PATH_X
 if test -n "${x_includes}"; then x_cflags="-I${x_includes}"; fi
 if test -n "${x_libraries}"; then x_libs="-I${x_libraries}"; fi
 
-AC_CHECK_LIB(X11, XOpenDisplay,
+ac_cv_my_have_x11=no
+AS_IF([test "x$with_x11" != xno],
+[AC_CHECK_LIB(X11, XOpenDisplay,
   [ac_cv_my_have_x11=yes
    X_CFLAGS="${x_cflags}"
    X_LIBS="${x_libs} -lX11"],
   [ac_cv_my_have_x11=no],
- [[${x_libs}]])
+  [[${x_libs}]])])
 AM_CONDITIONAL(HAVE_X11, test "${ac_cv_my_have_x11}" = "yes")
 AC_SUBST(X_CFLAGS)
 AC_SUBST(X_LIBS)
 
+ac_cv_my_have_xt=no
+AS_IF([test "x$with_xt" != xno],
+[AC_CHECK_LIB(Xt, XtFree,
  if test "${cross_compiling}" = "no"; then
-  AC_CHECK_LIB(Xt, XtFree,
     [ac_cv_my_have_xt=yes
      AC_CHECK_LIB(Xmu, XmuDrawLogo,
       [XT_CFLAGS="${x_cflags}"
@@ -505,27 +527,26 @@ if test "${cross_compiling}" = "no"; then
       [[-lXt -lSM -lICE -lXext -lX11 ${x_libs}]])],
     [ac_cv_my_have_xt=no],
     [[-lSM -lICE -lXext -lX11 ${x_libs}]])
-else
-  ac_cv_my_have_xt=no
-fi
+ fi])
 AM_CONDITIONAL(HAVE_XT, test "${ac_cv_my_have_xt}" = "yes")
 AC_SUBST(XT_CFLAGS)
 AC_SUBST(XT_LIBS)
 
-if test "${cross_compiling}" = "no"; then
+ac_cv_my_have_xaw=no
+AS_IF([test "x$with_xaw" != xno],
+[if test "${cross_compiling}" = "no"; then
    AC_CHECK_LIB(Xaw, XawTextSearch,
     [ac_cv_my_have_xaw=yes
      XAW_CFLAGS="${x_cflags}"
      XAW_LIBS="${x_libs} -lXaw ${XT_LIBS}"],
     [ac_cv_my_have_xaw=no],
     [[${XT_LIBS}]])
-else
-  ac_cv_my_have_xaw="no (cross-compiling)"
-fi
+ fi])
 AM_CONDITIONAL(HAVE_XAW, test "${ac_cv_my_have_xaw}" = "yes")
 AC_SUBST(XAW_CFLAGS)
 AC_SUBST(XAW_LIBS)
 
+ac_cv_my_have_motif=no
 if test "${cross_compiling}" = "no"; then
   AC_CHECK_LIB(Xm, XmStringConcat,
    [ac_cv_my_have_motif=yes
@@ -533,8 +554,6 @@ if test "${cross_compiling}" = "no"; then
     MOTIF_LIBS="${x_libs} -lXm ${XT_LIBS}"],
    [ac_cv_my_have_motif=no],
    [[${XT_LIBS}]])
-else
-  ac_cv_my_have_motif="no (cross-compiling)"
 fi
 AM_CONDITIONAL(HAVE_MOTIF, test "${ac_cv_my_have_motif}" = "yes")
 AC_SUBST(MOTIF_CFLAGS)