pthreads seem to be fully supported on Linux and Android which allows to remove many #ifdefs.

Also OS::Sleep(interval_) is used to pause sampling thread on all platforms. It makes no sense to send signal once 900mks to compensate 100mks delay on signal delivery as the signals would be delivered once 900mks.

BUG=None

Review URL: https://codereview.chromium.org/14238007

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14278 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Handle OOM failures correctly in the CEntryStub when embedders set V8::IgnoreOutOfMemoryException()

BUG=chromium:231217

Review URL: https://codereview.chromium.org/14066009

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14279 ce2b1a6d-e550-0410-aec6-3dcde31c8c00