Fix typo in comment.

Backpatch to 9.4 to minimize possible conflicts.

Author: kgrittn

src/include/utils/tqual.h

@@ -91,7 +91,7 @@ extern void HeapTupleSetHintBits(HeapTupleHeader tuple, Buffer buffer,
 extern bool HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple);
 
 /*
- * To avoid leaking to much knowledge about reorderbuffer implementation
+ * To avoid leaking too much knowledge about reorderbuffer implementation
  * details this is implemented in reorderbuffer.c not tqual.c.
  */
 extern bool ResolveCminCmaxDuringDecoding(struct HTAB *tuplecid_data,