Fix function name reference in comment

Ensure that we refer to the function being used, rather than the
name of the resulting function in question.

Author: Paul A Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CA+renyVZNiHEv5ceKDjA4j5xC6NT6mRuW33BDERBQMi_90_t6A@mail.gmail.com

src/backend/utils/cache/syscache.c

@@ -396,7 +396,7 @@ SearchSysCacheCopy(int cacheId,
 /*
  * SearchSysCacheLockedCopy1
  *
- * Meld SearchSysCacheLockedCopy1 with SearchSysCacheCopy().  After the
+ * Meld SearchSysCacheLocked1 with SearchSysCacheCopy().  After the
  * caller's heap_update(), it should UnlockTuple(InplaceUpdateTupleLock) and
  * heap_freetuple().
  */