patch 8.0.0180: error E937 is used twice

Problem:    Error E937 is used both for duplicate key in JSON and for trying
            to delete a buffer that is in use.
Solution:   Rename the JSON error to E938. (Norio Takagi, closes #1376)
diff --git a/src/version.c b/src/version.c
index dd5f700..7b576af 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    180,
+/**/
     179,
 /**/
     178,