Merge pull request #131 from sureshsundriyal/master

[build] Make sure readline has the necessary symbols.

Fixes #122

m4/lnav_with_readline.m4

@@ -27,7 +27,10 @@ AC_DEFUN([AX_PATH_LIB_READLINE],
             AC_MSG_ERROR([readline library not found])
         )dnl
         AS_VAR_SET([READLINE_CFLAGS], ["-I$with_readline/include"])
+        AS_VAR_SET([READLINE_SAVED_LDFLAGS], ["$LDFLAGS"])
         LNAV_ADDTO(CPPFLAGS, ["-I$with_readline/include"])
+        dnl We want the provided path to be the first in the search order.
+        LDFLAGS="-L$with_readline/lib $LDFLAGS"
         ]dnl
     )
 
@@ -43,6 +46,18 @@ AC_DEFUN([AX_PATH_LIB_READLINE],
         [AC_MSG_ERROR([readline headers not found])]
     )
 
+    dnl Ensure that the readline library has the required symbols.
+    dnl i.e. We haven't picked up editline.
+    AC_SEARCH_LIBS([history_set_history_state], [readline],
+        [
+        AS_VAR_SET_IF([READLINE_SAVED_LDFLAGS],
+            AS_VAR_SET([LDFLAGS], ["$READLINE_SAVED_LDFLAGS"])
+        )
+        ],
+        AC_MSG_ERROR([libreadline does not have the required symbols. editline possibly masquerading as readline.])
+        [$CURSES]
+    )
+
     AC_SUBST([READLINE_LIBS])
     AC_SUBST([READLINE_CFLAGS])
     ]dnl