testsuite: Suppress ticks in T4918 output

As noted in #16741, this test otherwise breaks when `base` is compiled
with `-g`.

testsuite/tests/simplCore/should_compile/Makefile

@@ -106,11 +106,13 @@ T4903:
 	'$(TEST_HC)' $(TEST_HC_OPTS) -c -O T4903a.hs -dcore-lint
 	'$(TEST_HC)' $(TEST_HC_OPTS) -c -O T4903.hs -dcore-lint
 
+# N.B. Suppress ticks to ensure that the test result doesn't change if `base`
+# is compiled with -g. See #16741.
 T4918:
 	$(RM) -f T4918.hi T4918.o T4918a.hi T4918a.o
 	'$(TEST_HC)' $(TEST_HC_OPTS) -c -O T4918a.hs
 	'$(TEST_HC)' $(TEST_HC_OPTS) -c -O T4918.hs
-	'$(TEST_HC)' $(TEST_HC_OPTS) --show-iface T4918.hi | grep 'C#'
+	'$(TEST_HC)' $(TEST_HC_OPTS) -dsuppress-ticks --show-iface T4918.hi | grep 'C#'
 
 EvalTest:
 	'$(TEST_HC)' $(TEST_HC_OPTS) -c -O EvalTest.hs -ddump-simpl -dsuppress-uniques | grep 'rght.*Dmd' | sed 's/^ *//'