Test for $with_system_argp != no, rather than = yes.

Rev: configure.ac:1.94

configure.ac

@@ -584,10 +584,15 @@ fi
 
 # Test if the libc includes a good enough argp.
 # FIXME: Doesn't check for the argp-help bug.
-if test x$with_system_argp = xyes ; then
+if test x$with_system_argp != xno ; then
   LSH_LIB_ARGP(,with_system_argp=no)
 fi
 
+AH_TEMPLATE([HAVE_ARGP_PARSE], [Define to use the argp parser in libc])
+if test x$with_system_argp != xno ; then
+  AC_DEFINE(HAVE_ARGP_PARSE)
+fi
+
 BUILD_SUBDIRS=''
 LIB_ARGP=''
 if test x$with_system_argp = xno ; then