Bump mmtk-core, ruby and deps revisions #189

Job	Run time
Build and test (normal, debug, StickyImmix)	5m 7s
Build and test (normal, debug, MarkSweep)	7m 33s
Build and test (normal, release, Immix)	19m 34s
Build and test (special, debug, StickyImmix, yjit)	5m 8s
Build and test (special, release, StickyImmix, yjit)	8m 26s
Build and test (normal, release, MarkSweep)	21m 51s
Style check	1m 21s
Build and test (special, vanilla)	4m 12s
Build and test (normal, release, StickyImmix)	8m 26s
Build and test (normal, debug, Immix)	6m 52s
	1h 28m 30s

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