Failures on Debian-s390x-native-extended-gdbserver-m64, branch master

[sergiodj+buildbot@sergiodj.net]

Buildslave:
	debian-jessie-s390x-1

Full Build URL:
	<http://gdb-build.sergiodj.net/builders/Debian-s390x-native-extended-gdbserver-m64/builds/4062>

Commit(s) tested:
	9bcbdca808b5f9fec6217d20bd4b48a56008c460

Author(s) (in the same order as the commits):
	Pedro Alves <palves@redhat.com>

Subject:
	PR remote/21188: Fix remote serial timeout

Testsuite log (gdb.sum and gdb.log) URL(s):
	<http://gdb-build.sergiodj.net/results/Debian-s390x-native-extended-gdbserver-m64/9b/9bcbdca808b5f9fec6217d20bd4b48a56008c460/>