[patch] skip tests that use cd for remote hosts

[Janis Johnson <janis_johnson at mentor dot com>]

Several GDB tests change directory before compiling the test program in
order to test source file names that include directories.  This doesn't
work on a remote host because default_target_compile in DejaGnu's
target.exp copies each source file with "[remote_download host $x]"
which uses "[file tail $file] to strip off the directory of each file.
If the source directory is remote mounted on the host, this also leaves
copied files in the source directory.

A similar skip is already used in gdb.test/fullname.exp:

    # We rely on being able to copy things around.

    if { [is_remote host] } {
        untested "setting breakpoints by full path"
        return -1
    }

This patch causes three GDB tests that use "cd" to be skipped for a
remote host.  For gdb.base/fullpath-expand.exp this eliminates two
failures and prevents the test from leaving files fullpath-expand.c
and fullpath-expand-func.c in gdb/testsuite.  For
gdb.base/realname-expand.exp it eliminates two failures.  For
gdb.linespec/macro-relative.exp it prevents file macro-relative.c from
being left in gdb/testsuite/gdb.linespec/base/two.

I'm not set up to test this with a build of upstream gdb but have tested
it with a remote host using arm-none-gnueabi with relavent DejaGnu and
GDB tests that are the same as in upstream.  OK?

Janis Johnson
CodeSourcery / Mentor Graphics