Tweak TH_Depends

It was explicitly removing the program inbetween the two runs, but
I don't see why that should be necessary.

testsuite/tests/th/Makefile

@@ -26,9 +26,6 @@ TH_Depends:
 	echo "first run" > TH_Depends_external.txt
 	'$(TEST_HC)' $(TEST_HC_OPTS) --make -v0 TH_Depends
 	./TH_Depends
-# Remove the executable, as GHC won't relink if the timestamps seem to
-# be the same
-	$(RM) TH_Depends TH_Depends.exe
 	sleep 2
 	echo "second run" > TH_Depends_external.txt
 	'$(TEST_HC)' $(TEST_HC_OPTS) --make -v0 TH_Depends