dg-options after board/cflags

[Maciej W. Rozycki]

On Wed, 2 Sep 2020, Jose E. Marchesi via Gcc-patches wrote:

> Your patch dealt with board/multilib_flags, but the same problem exists
> for board/cflags and many other flag-containing options.

 What's the use case for that?  IIUC board flags are supposed to be ones 
that are absolutely required for executables to run with a given board, 
such as multilib selection, special linker scripts, non-standard run-time 
library paths, etc.  These must not be overridden by test cases or they 
will inevitably fail.

  Maciej