Cleanup some trivial TODOs.

1) There's no reason or way to support boot_clock for waiting for
   property changes, since the underlying futex_wait uses
   CLOCK_MONOTONIC.  We probably wouldn't want boot_clock even if it
   did, since it doesn't make sense to consider the time a device was
   suspending in the timeout for waiting for a property to change.
2) The init tokenizer has been essentially unchanged for a decade,
   there's no motivation to 'fix' it to not require a trailing
   newline.
3) The ueventd TODO regarding moving vendor specific ueventd.rc
   entries out of rootdir has been fixed.

Test: n/a
Change-Id: I3b68e3d2f25cbd539f9f8ff526669b8af04d833d
diff --git a/properties.cpp b/properties.cpp
index 35e41a8..5c9ec7e 100644
--- a/properties.cpp
+++ b/properties.cpp
@@ -133,7 +133,6 @@
   ts.tv_nsec = ns.count();
 }
 
-// TODO: boot_clock?
 using AbsTime = std::chrono::time_point<std::chrono::steady_clock>;
 
 static void UpdateTimeSpec(timespec& ts, std::chrono::milliseconds relative_timeout,