Add a way to SuspendAll for a long duration

Hprof uses this mode to not cause thread suspend timeouts if GC tries
while the hprof dump is running.

(cherry picked from commit 77be6635f9b07a8a794924c5fb9b071949776a6d)

Bug: 21063989
Change-Id: Ic6304620afd1489719a7e0e4299f829c90fe27cc
3 files changed