fix macos build

[lovettchris]

Fix a build break on macOS by using different version of pthread_setname_np

[rajat2004]

@lovettchris It first encounters the missing prctl header file

/Users/user/Documents/la/AirSim/MavLinkCom/common_utils/ThreadUtils.cpp:9:10: fatal error: 'sys/prctl.h' file not found
#include <sys/prctl.h>
^~~~~~~~~~~~~
1 error generated.

Need to remove that as well

Reproduced the error on Travis - https://travis-ci.com/rajat2004/AirSim/builds/144190684

[rajat2004]

Extra commit here - rajat2004@0983900
Working Travis build- https://travis-ci.com/rajat2004/AirSim/builds/144194609

PR for adding Travis builds - #2356

[lovettchris]

yes indeed, I forgot to remove the #include after switching to pthread_setname_np. This fix is now included