testsuite: Mark the kill in gdbserver_run as optional

This matches the kill in gdb_file_cmd, and ensures that the command is not
sent to the gdb.in file.

When gdb.in is used as a batch file, any kill commands run before the target
is started will cause gdb to stop processing commands.

gdb/testsuite/ChangeLog:

	* lib/gdbserver-support.exp (gdbserver_run): Mark kill as optional.
2 files changed