Don't lock the struct unveil being created in the child when cloning the
parent's during fork()
witness reports from ajacoutot@ and Hrvoje Popovski (hrvoje (at) srce.hr)
Delete obsolete bits in a comment: mcontext is gone and struct reg is no
longer required to be layout compatible with struct trapframe
noted by Benjamin Baier (programmer (at) netzbasis.de)
newlen was a dead store, but what we could use is oldlen to
simplify the code.
Pointed out by daniel@ with the help of their friend gcc9
rename PIPE_WANT to PIPE_WANTD.
PIPE_WANT flag is used for signaling the pipe is about to be run-down.
Pending readers/writers will wakeup the closing thread which is waiting.
We already have PIPE_WANTR, PIPE_WANTW and PIPE_LWANT flags, so
PIPE_WANT isn't really descriptive.
No functional changes intented.
ok visa@ anton@ mpi@