Reorder headers to follow the Google C++ Style Guide:
> In dir/foo.cc or dir/foo_test.cc:
>
> 1. dir2/foo2.h.
> 2. A blank line
> 3. C system headers (more precisely: headers in angle brackets with
the .h extension), e.g., <unistd.h>, <stdlib.h>.
> 4. A blank line
> 5. C++ standard library headers (without file extension), e.g.,
<algorithm>, <cstddef>.
> 6. A blank line
> 7. Other libraries' .h files.
> 8. A blank line
> 9. Your project's .h files.
https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes
Note:
* An xHE-AAC capable encoder will auto adjust the user-specified SAP/RAP
value to the allowed grid where SAP/RAPs can occur.
e.g.: `-rapInterval 5000` (5s) may result in actual SAPs/RAPs every
4.984s.
* To ensure SAP/RAP starts a new segment, Shaka needs to executed with a
"--segment_duration" is less than or equal to that adjusted value.
* If every SAP/RAP should trigger a new segment, just set the segment
length to a very low value e.g.: `--segment_duration 0.1`
Fixes#387.
Note that the output will not play in Chrome until the Chrome bug
https://crbug.com/837832 is fixed.
Change-Id: Ic3e917161cedfa773c0a18b4a5d7b1254c6f1313