win32: adb start-server shows stdout/stderr output from actual server

When launching the adb server (typically from adb start-server),
redirect stdout/stderr to anonymous pipes which are read by threads in
the parent process, to make error diagnosis easier.

If there is an error during adb start-server, the output looks like:

> adb start-server
* daemon not running. starting it now on port 5037 *
error: could not blah                 # from server process
could not read ok from ADB Server     # from launch_server
* failed to start daemon *            # from adb_connect
error: cannot connect to daemon       # from adb_commandline

Fix handle-leaks in launch_server by using new unique_handle class
that is based on std::unique_ptr.

In the server, close stdin and redirect to adb.log *before* sending the
ACK, so that any errors are reported early instead of after the ACK.

Change-Id: I943881210a0ea9458fc36851339f916c3d6a0830
Signed-off-by: Spencer Low <CompareAndSwap@gmail.com>