[PATCH] simplify ulimit implementation

[Roland McGrath]

I don't think losing __UL_GETMAXBRK is really a problem.  The reason for
removing it was not specific to Linux, just to the implementation being in
a shared library.  It could be implemented in a shared library, at the cost
of a GOT reloc for _etext to get the main executable's value (or
conversely, perhaps some grovelling in dynamic linker data structures for
the shared case).  But given that the current implementation usable on the
Hurd will yield utterly useless values, the case for having it at all is
inordinately weak.