Adjust spellings of forms of "cancel"

src/backend/utils/adt/misc.c

@@ -532,7 +532,7 @@ pg_sleep(PG_FUNCTION_ARGS)
 	 * By computing the intended stop time initially, we avoid accumulation of
 	 * extra delay across multiple sleeps.  This also ensures we won't delay
 	 * less than the specified time when WaitLatch is terminated early by a
-	 * non-query-cancelling signal such as SIGHUP.
+	 * non-query-canceling signal such as SIGHUP.
 	 */
 
 #ifdef HAVE_INT64_TIMESTAMP

src/backend/utils/adt/numeric.c

@@ -7289,7 +7289,7 @@ div_var_fast(NumericVar *var1, NumericVar *var2, NumericVar *result,
 		 * But having said that: div[qi] can be more than INT_MAX/NBASE, as
 		 * noted above, which means that the product div[qi] * NBASE *can*
 		 * overflow.  When that happens, adding it to div[qi + 1] will always
-		 * cause a cancelling overflow so that the end result is correct.  We
+		 * cause a canceling overflow so that the end result is correct.  We
 		 * could avoid the intermediate overflow by doing the multiplication
 		 * and addition in int64 arithmetic, but so far there appears no need.
 		 */