MEDIUM: stream-int: temporarily make si_chk_rcv() take care of SI_FL_WAIT_ROOM

MEDIUM: stream-int: temporarily make si_chk_rcv() take care of SI_FL_WAIT_ROOM

This flag should already be cleared before calling the *chk_rcv() functions.
Before adapting all call places, let's first make sure si_chk_rcv() clears
it before calling them so that these functions do not have to check it again
and so that they do not adjust it. This function will only call the lower
layers if the SI_FL_WANT_PUT flag is present so that the endpoint can decide
not to be called (as done with applets).