Fix mi_expect_stop for non-zero exit codes

The message displayed by gdb is different when the inferior exits with
zero and non-zero values, this fix takes that into account.

gdb/testsuite/ChangeLog:
2014-05-13  Simon Marchi  <simon.marchi@ericsson.com>

	* lib/mi-support.exp (mi_expect_stop): Expect message for
	inferiors that exit with non-zero exit code.
Fix argument passing in mi_run_cmd_full

Passing arguments did not work when use_mi_command was set.

gdb/testsuite/ChangeLog:
2014-05-13  Simon Marchi  <simon.marchi@ericsson.com>

	* lib/mi-support.exp (mi_run_cmd_full): Set arguments by calling
	"-exec-arguments" or "set args" before running the inferior.