vm: fix race condition in timeout

Eliminate a race condition between uv_async_send and the closing of the
corresponding handle.

Also made errors in Watchdog constructor call abort()

Fixes #6088
windows: fix dns lookup of localhost with ipv6

Removing a hack intended to shortcut the resolution of 'localhost'
but which doesn't work for ipv6.
This was introduced in 2876141c4292791bc12c0b8701dbcc366dde7297.
However it seems that the problems that this was trying to
circumvent has gone away ages ago, when dns resolution on
Windows started relying on Win32 GetAddrInfoW, which was
probably with be2320d408de89054b254a0c812280054d946490.

Fixes test-net-connect-options-ipv6.js on Windows.
deps: v8 apply temporary fix until backport

Fix node.js debug build with a temporary v8 fix until the v8 team will
backport the fix from the more recent version of v8.

see https://code.google.com/p/v8/issues/detail?id=3062
crypto: remove unnecessary OpenSSL_add_all_digests

`OpenSSL_add_all_algorithms` implicitly adds both digests and
ciphers. No need in calling `OpenSSL_add_all_digests` after it.
test: fix flaky unit test test-fs-realpath.js

The test was not performing proper cleanup and so it would
fail if run more than one time on the same machine.