these all now use the shared __randname function internally, rather
than duplicating logic for producing a random name. incorrect usage of
the access syscall (which works with real uid/gid, not effective) has
been removed, along with unnecessary heavy dependencies like snprintf.
open is handled specially because it is used from so many places, in
so many variants (2 or 3 arguments, setting errno or not, and
cancellable or not). trying to do it as a function would not only
increase bloat, but would also risk subtle breakage.
this is the first step towards supporting "new" archs where linux
lacks "old" syscalls.
don't waste time (and significant code size due to function call
overhead!) setting errno when the result of a syscall does not matter
or when it can't fail.
