Improve missing header message

	* configure.ac: Note that we also need Xt headers as newer distros
	tend to package Xt headers separately from core X11.

Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>

diff --git a/configure.ac b/configure.ac
index dfb737b..51f6041 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -2504,7 +2504,7 @@ dnl   fi
 
        dnl make sure we can find Intrinsic.h
        AC_CHECK_HEADER([X11/Intrinsic.h], [],
-               [AC_MSG_ERROR([Unable to find X11 header files. Try using --x-includes=<path> if you know the path, or --with-x=no to disable X11 support.])])
+               [AC_MSG_ERROR([Unable to find X11 and/or Xt header files. Try using --x-includes=<path> if you know the path, or --with-x=no to disable X11 support.])])
 
        dnl Check some more headers
        AC_CHECK_HEADERS([X11/Intrinsic.h X11/StringDefs.h X11/Shell.h X11/ShellP.h],