patch 7.4.2121

Problem:    No easy way to check if lambda and closure are supported.
Solution:   Add the +lambda feature.

src/version.c

@@ -304,6 +304,11 @@ static char *(features[]) =
 #else
 	"-keymap",
 #endif
+#ifdef FEAT_EVAL
+	"+lambda",
+#else
+	"-lambda",
+#endif
 #ifdef FEAT_LANGMAP
 	"+langmap",
 #else
@@ -758,6 +763,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2121,
 /**/
     2120,
 /**/