ModGC

Fix an effects bug that missed some control flow instructions #2743

Job	Run time
check (default, macos-latest)	8m 41s
check (mmtk, release, ubuntu-latest)	11m 11s
check (default, ubuntu-latest)	7m 34s
check (mmtk, release, macos-latest)	11m 24s
	38m 50s

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