One set of tests in gdb.base/source-dir.exp does a lot of complicated 
directory manipulations to force a specific DW_AT_comp_dir format and 
gdb directory search path.  As it's written, everything assumes host == 
build, and it does not seem to me that there is any obvious way to 
rewrite this so it will work in general on remote host.  For instance, 
our harness for testing on remote Windows host normally does all 
compilation and GDB execution in $cwd using relative pathnames and I'm 
not sure all these directory tricks would set up the scenario it's 
trying to test even if they were correctly performed on host rather than 
build.  So I think it's reasonable just to disable this on remote host 
instead.

I also noted that it's using the wrong search path syntax for Windows 
host in the "set directories" command and conditionalized that while I 
was looking at it.  That's a necessary fix to make this work in a 
situation where host == build and it's Windows, but I'm not actually set 
up to test that it's sufficient, too.

OK to check this in?

-Sandra