build: remove unneeded define in uv.gyp

It's a leftover from the days libuv bundled c-ares.
build: use same CFLAGS in autotools build as in gyp

Closes #1362
unix, windows: add uv_fileno

Returns the platform specific file descriptor for handles that are
backed by one. The datatype is abstracted as uv_os_fd_t, which maps to
int on Unices and HANDLE on Windows.

Users can use this function to set specific socket options, for example,
in a non portable way.

This function is essentially a shotgun, you better be careful with
whatever you do with it, don't blame me if you used it to get the fd of
a stream, close it yourself and expect things to Just Work.
windows: make sure sockets and handles are reset on close

Set the socket to INVALID_SOCKET foir TCP and UDP handles and
the handle to INVALID_HANDLE_VALUE on TTY handles after closing them.
windows: fix buffer leak after failed udp send

Fixes #1426

Signed-off-by: Saúl Ibarra Corretgé <saghul@gmail.com>
core: update version to 1.0.0
doc: update README with versioning information
core: add a reserved field to uv_handle_t and uv_req_t

Just in case we need to work hard in keeping ABI compatibility.
windows: remove duplicated field

Fixes build
unix: simplify how process handle queue is managed
unix: stop child process watcher after last one exits