adb: logging: newlines, thread ids, error code overwriting

Add missing \n to uses of legacy D() macro. This should make the legacy
logging easier to read (and harder to miss important stuff).

On POSIX, use gettid() from libcutils instead of pthread_self() so that
the output shows a more reasonable number instead of a pointer value.
This should be ok since libbase's logging already uses gettid().

Win32:

Don't let the Win32 last error get overwritten by API calls after the
original error'ing API. When encountering an unknown error, log the
specific error code.

Change-Id: Ib8f72754efa7ba895d2f1cd914251fec2a1d894c
Signed-off-by: Spencer Low <CompareAndSwap@gmail.com>