Fix clearing mutable flags on ef_close()

Fix clearing mutable flags on ef_close()

Make ef_close() clear them always, even for views.  Harmless, as
ef_open_view() always sets the same flags.

Drop redundant assignment to ep->flags in ef_open().  ef_close()
clears mutable flags, no need to clear them some more right before
calling it.  Missed in commit 3eb3607f, v4.3.0.