RFC: add relative file name handling for linespecs

[Tom Tromey]

>>>>> "Joel" == Joel Brobecker <brobecker@adacore.com> writes:

Joel> One thing I noticed is that we might want to apply the same treatement
Joel> to the "clear" command... It uses the filename_cmp function directly,
Joel> instead of using the FILENAME_CMP macro.

Thanks for noticing this.
I fixed this in my latest; I'm re-testing it all now.

Tom