More carefully checking for libreadline suitability

acinclude.m4

@@ -131,6 +131,41 @@ iconv_close(cd);
 ])
 
 
+dnl LIBBURNIA_ASSERT_READLINE disables xorriso readline if not all needed
+dnl functions are present
+AC_DEFUN([LIBBURNIA_ASSERT_READLINE],
+[
+  if test x$XORRISO_ASSUME_READLINE = x
+  then
+    dnl Check for the essential gestures of libisofs/util.c
+    AC_MSG_CHECKING([for desired functions in libreadline])
+    libburnia_save_LIBS="$LIBS"
+    LIBS="$LIBS -lreadline"
+    AC_TRY_LINK([
+#include <ctype.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <readline/readline.h>
+#include <readline/history.h>],
+[HIST_ENTRY **hl;
+readline("");
+add_history("");
+hl= history_list();
+], [readline_test="yes"], [readline_test="no"]
+    )
+    AC_MSG_RESULT([$readline_test])
+    if test x$readline_test = xno
+    then
+        READLINE_DEF=
+        LIBS="$libburnia_save_LIBS"
+    fi
+  fi
+])
+
+
 dnl LIBBURNIA_SET_PKGCONFIG determines the install directory for the *.pc file.
 dnl Important: Must be performed _after_ TARGET_SHIZZLE
 dnl