VxWorks build failure in OS_FileChmod_Impl

[jphickey]

Describe the bug
Failure occurs on a VxWorks 6.9 build:

/home/jphickey/cfecfs/github/osal/src/os/portable/os-impl-posix-files.c: In function 'OS_FileChmod_Impl':
/home/jphickey/cfecfs/github/osal/src/os/portable/os-impl-posix-files.c:202: error: too few arguments to function 'open'
make[7]: *** [osal/vxworks_impl/CMakeFiles/osal_vxworks_impl.dir/__/portable/os-impl-posix-files.c.obj] Error 1

Looks like this was recently introduced in the 2020-11-03 IC in via #639 ...

To Reproduce
Build for MCP750 / vxworks 6.9 platform using standard method and default config.

Expected behavior
Build succeeds.

Code snips
Looks like VxWorks 6.9 doesn't implement open() per POSIX specs - it only has the 3 argument form (with mode) and not the 2 argument form.

System observed on:
VxWorks 6.9

Additional context
Hopefully we can get a CI that includes VxWorks....

Reporter Info
Joseph Hickey, Vantage Systems, Inc.

[jphickey]

Originally noticed by @dmknutsen .

Also this affects the same line of code that is already a subject of #650 .

For some reason I thought we made this change to use a file descriptor and fchmod a long time ago, but in reality it was only merged last week.