There was auto-reconnecting by slave earlier than a prescribed by slave_net_timeout value.
The issue happened on 64bit solaris that spotted rather incorrect casting of 
the ulong slave_net_timeout into the uint of mysql.options.read_timeout.

Notice, that there is no reason for slave_net_timeout to be of type of ulong.
Since it's primarily passed as arg to mysql_options the type can be made
as uint to avoid all conversion hassles.
That's what the fixes are made.
A "side" effect of the patch is a new value for the max of slave_net_timeout
to be the max of the unsigned int type (therefore to vary across platforms).

Note, a regression test can't be made to run reliably without making it to last over some 
20 secs. That's why it is placed in suite/large_tests.