Improve handling SIGURG and OOB commands on the control channel.
Improve handling SIGURG and OOB commands on the control channel.

The major change is to process STAT sent as an OOB command w/o
breaking the current data transfer.  As a side effect, this gives
better error checking in the code performing data transfers.

A lesser, but in no way cosmetic, change is using the flag `recvurg'
in the only signal-safe way that has been blessed by SUSv3.  The
other flag, `transflag,' becomes private to the SIGURG machinery,
serves debugging purposes only, and may be dropped in the future.

The `byte_count' global variable is now accounting bytes actually
transferred over the network.  This can give status messages looking
strange, like "X of Y bytes transferred," where X > Y, but that has
more sense than trying to compensate for combinations of data formats
on the server and client when transferring ASCII type data.  BTW,
getting the size of a file in advance is unreliable for a number of
reasons in the first place.  See question 18.8 of the Infrequently
Asked Questions in comp.lang.c for details.

PR:		bin/52072
Tested by:	Nick Leuta (earlier versions), a stress-testing tool (final)
MFC after:	1 month

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