add interface and basic implementaion and UT for EncoderStatistics
Remove the "platform-" prefix from common shared makefiles

This makes it clearer which ones actually are real platforms
(chosen automatically or explicitly via "make ARCH=foo") and which
ones just are shared helpers.
add UT for sim-SVC switch
        add a thread name for easier profiling
Merge pull request #1432 from mstorsjo/rename-makefiles

Remove the "platform-" prefix from common shared makefiles
fix crash bug of sps/pps
reformat cpp files for next release
fix bug in set option return value
reformat cpp files for unit tests
Merge pull request #1438 from huili2/EC_crashfix

fix crash bug of sps/pps
Merge pull request #1429 from sijchen/add_statistics1

[Encoder] add EncoderStatistics
Merge pull request #1437 from sijchen/after_review2

[Encoder] add a thread name for easier profiling
Add casts to avoid warnings about comparison between signed and unsigned
Only use pthread_setname_np on Android >= 9 (2.3)

Older versions of Android don't have this function.
Merge pull request #1441 from mstorsjo/avoid-warnings

Add casts to avoid warnings about comparison between signed and unsigned
Merge pull request #1442 from mstorsjo/android-pthread-setname

Only use pthread_setname_np on Android >= 9 (2.3)
Merge pull request #1439 from sijchen/for_format

[Reformat] format cpp files for next release
Merge pull request #1440 from shihuade/APIUTV1.4

fix bug in set option return value
Merge pull request #1443 from dongzha/AddUTSwitch

add UT for sim-SVC layer switch
    fix a small range of slice idx