BUG/MINOR: cfgparse/server: increment the extra keyword counter one at a time

This was introduced in previous commit 49c2b45c1 ("MINOR: cfgparse/server:
try to fix spelling mistakes on server lines"), the loop was changed but
the increment left. No backport is needed.
diff --git a/src/server.c b/src/server.c
index 8b2dd4f..ed9925e 100644
--- a/src/server.c
+++ b/src/server.c
@@ -335,7 +335,6 @@
 			best_dist = dist;
 			best_ptr = *extra;
 		}
-		extra++;
 	}
 
 	if (best_dist > 2 * strlen(word) || (best_ptr && best_dist > 2 * strlen(best_ptr)))