The existing implementation used the same logic as is found in
mach_msg_server(), but that logic seems incorrect. When the caller wants
to retry a mach_msg() receive of a too-large message that returns
MACH_RCV_TOO_LARGE, there’s no harm in attempting the receive with a
larger buffer initially. On the other hand, if the caller does not want
to retry such mach_msg() receive attempts, it’s an indication that the
caller is expecting to be intolerant of too-large messages, and there’s
no need to attempt the receive with a buffer any larger than requested.
TEST=util_test
R=rsesek@chromium.org
Review URL: https://codereview.chromium.org/753363003
a685942342