Raise the timeout for 670-bitstring-type-check.

Also make run-test-jar support fractional time multipliers.

Test: art/test/testrunner/testrunner.py --target --64 --optimizing -t 670
Test: art/test/testrunner/testrunner.py --target --64 --optimizing -t 670
  with DEV_MODE enabled to check the timeout argument
Test: art/test/testrunner/testrunner.py --target --64 --optimizing -t 670
  with ART_TIME_OUT_MULTIPLIER=1.3465323455433 to ensure fractional digits work
Bug: 141742445
Change-Id: Ief56884a27b3090fbead05df78fc09712823cd61
2 files changed