Add conditional include of vxWorks.h for kernel mode

[Mike Stump]

On Dec 22, 2020, at 1:14 PM, Alexandre Oliva <oliva@adacore.com> wrote:
> 
> In kernel mode, an application must include vxWorks.h before any other
> system header, this patch adds exactly that to the test that were
> failing due to a missing declaration that was found in vxWorks.h.

I'm inclined to rather have a -include vxWorks.h method where you figure out when this should be done and add it to the command line flags as necessary, that, or have the gcc includes mechanism automatically include the file itself when those conditions are present.  Although, yet more possibilities exist, like knowing what from that file is necessary, and builtinizing that content so that the tests pass anyway.

Thoughts?