fed3636f12
Add 'StressIGVN' option to let C2 randomize IGVN worklist order. When enabled, the worklist is shuffled before each main run of the IGVN loop. Also add 'StressSeed=N' option to specify the seed. If the seed is not specified, a random one is generated. In either case, the seed is logged if 'LogCompilation' is enabled. The new options are declared as production+diagnostic for consistency with the existing 'StressLCM' and 'StressGCM' options. Reviewed-by: kvn, chagedorn, thartmann