gdb_remote: Fix debug symbol check errors

Move debug symbol checks down to after finding remote file path
by pid. This fixes the false complaints about missing debug symbols
when --remote_pid flag is used.

BUG=brillo:474
TEST=Manual tests

Change-Id: I927581d1801f7d018a7f420e8b0ddd104772f1df
Reviewed-on: https://chromium-review.googlesource.com/256733
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Yiming Chen <yimingc@chromium.org>
Tested-by: Yiming Chen <yimingc@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
1 file changed