MachMessageServer test: deal with short receive queue lengths on 10.10

MachMessageServer test: deal with short receive queue lengths on 10.10.

The queue length of a new receive port appears to be 2 on Mac OS X 10.10
DP8 14A361c. The value of MACH_PORT_QLIMIT_DEFAULT in the 10.10 SDK is
still 5, so a read of the kernel source should be interesting, if we
ever get to see it.

In the meantime, mach_port_set_attributes() can be used to set a
traditional queue length.

TEST=util_test MachMessageServer.PersistentNonblockingFourMessages
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/8eec7874fd035bba7aadb469013e54730890b181

[Mark Mentovai, 2014-09-19 22:17:39]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2014-09-22 15:15:57]

LGTM

https://codereview.chromium.org/584293003/diff/1/util/mach/mach_message_serve...
File util/mach/mach_message_server_test.cc (right):

https://codereview.chromium.org/584293003/diff/1/util/mach/mach_message_serve...
util/mach/mach_message_server_test.cc:316: mach_port_limits limits;
= {} in case this struct ever grows?

[Mark Mentovai, 2014-09-22 17:15:20]

Committed patchset #3 (id:40001) manually as 8eec787 (presubmit successful).