I was seeing a failure in mi-solib.exp and traced it to the fact that
fullname=foo wasn't being emitted by gdb.
What gdb prints depends on the system library that is loaded and how
it was compiled. The presence of fullname= isn't germane to the regexp, so
this patch makes the fullname= parameter optional in the expected output.
Regression tested on amd64-linux.
I will check this in in a few days if there are no objections.