In
54deb01f00 vfs: Make OpenFile and friends return EINVAL if O_RDONLY and O_TRUNC
The generated file open_test.go was edited directly without editing
the generator.
This commit brings the generator make_open_tests.go back into line
with that edit. It also makes it so `go generate` can be used to
regenerate the tests.
Before this change Open("name", os.O_RDONLY|os.O_TRUNC) would have
truncated the file. This is what Linux does, but is counterintuitive.
POSIX states this is undefined, so return an error in this case
instead. This preserves the invariant O_RDONLY => file is not
changed.