patch 7.4.2050

Problem:    When using ":vimgrep" may end up with duplicate buffers.
Solution:   When adding an error list entry pass the buffer number if possible.

src/version.c

@@ -758,6 +758,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2050,
 /**/
     2049,
 /**/