Make soreceive(MSG_DONTWAIT) nonblocking. If MSG_DONTWAIT is passed into soreceive(), then pass in M_DONTWAIT to m_copym(). Also fix up error handling for the case where m_copym() returns failure.
Make soreceive(MSG_DONTWAIT) nonblocking. If MSG_DONTWAIT is passed into
soreceive(), then pass in M_DONTWAIT to m_copym(). Also fix up error
handling for the case where m_copym() returns failure.

Submitted by:	Mohan Srinivasan mohans at yahoo-inc dot com
Reviewed by:	rwatson

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