[PATCH] Skip jit tests for targets that don't support -lgccjit

[Jeff Law]

On Fri, 2020-05-08 at 12:12 -0700, H.J. Lu via Gcc-patches wrote:
> Since libgccjit.so is linked into jit tests, skip jit tests for targets
> that don't support -lgccjit.
> 
> OK for master?
> 
> H.J.
> ---
> 	PR jit/94778
> 	* jit.dg/jit.exp: Skip jit tests for targets that don't support
> 	-lgccjit.
> 	* lib/target-supports.exp (check_effective_target_lgccjit): New.
I believe the new dejagnu tests needs to be documented in sourcebuild.texi.

OK with the sourcebuild.texi changes included.

jeff