smalloc: check if obj has external data

PR-URL: https://github.com/joyent/node/pull/8655
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
build: fix build for SmartOS

This change in V8: https://code.google.com/p/v8/source/detail?r=22210
has introduced a method named OS::GetCurrentThreadId which fails to
compile on OSes where a "gettid" syscall does not exist.

This build issue has been fixed upstream by several changes:
- https://code.google.com/p/v8/source/detail?r=23459.
- https://codereview.chromium.org/649553002
- https://codereview.chromium.org/642223003

Another minor fix to the upstream changes was also necessary.
See https://code.google.com/p/v8/issues/detail?id=3620 for
more information.

The other build issue was due to the fact that alloca.h is not included
by other system includes on SmartOS, which is assumed by V8.

Built and tested on Linux, MacOS X, Windows and SmartOS.
test: more thorough tests for npm
npm: Upgrade to v2.1.6
deps: update uv to v1.0.0-rc2

PR-URL: https://github.com/joyent/node/pull/8566
Reviewed-by: Fedor Indutny <fedor@indutny.com>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
core: replace uv_fs_readdir with uv_fs_scandir

PR-URL: https://github.com/joyent/node/pull/8566
Reviewed-by: Fedor Indutny <fedor@indutny.com>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>
core: fix usage of uv_cwd

It was modified in libuv to be consistent with uv_exepath and not
include the trailing NULL byte in the returned size.

PR-URL: https://github.com/joyent/node/pull/8566
Reviewed-by: Fedor Indutny <fedor@indutny.com>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>