[Bug target/91050] -mdejagnu-cpu= does not affect the -m assembler option

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91050

--- Comment #8 from Alan Modra <amodra at gmail dot com> ---
Created attachment 46555
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46555&action=edit
assembler command line fixes

I'll happily handle the assembler command line problems.  Here's a lightly
tested patch.