_osmajor checks should be removed

[stsp]

There are a couple of cases, most
notably in sys/vfs/statfs.c, where
the libc checks if( 7 <= _osmajor && _osmajor < 10 )
and uses an extended functionality,
falling back to the basic functionality
otherwise.
The extended functionality block is
however properly implemented: it
falls back to the basic functionality
anyway, if the extended functions
failed.
There are many DOS clones around,
for which this check fails. Since the
code have the proper fallbacks anyway,
the _osmajor checks should be removed.

[jwt27]

Hm, not sure. There may be some obscure DOS versions/flavors that do something unexpected, instead of fail normally. I would assume those checks are there for a reason.

[stsp]

Maybe but so far they require me to
overwrite _osmajor.
Note that obscure doses must be checked
separately for a particular broken
functionality. Removing all doses from
the bicture by the reason that some of
them may be obscure, is not a solution.
And besides, there can be tsrs that add
the missing functionality to older doses
(like doslfn).