[patch 0/3] no MAX_ARG_PAGES -v2

This patch-set aims at removing the current limit on argv+env space aka.
MAX_ARG_PAGES.

The new mm is created before the binfmt code runs, the stack is placed at the
highest address supported by that architecture.

The argv+env data is then copied from the old mm into the new mm (which is
inactive at that time - this introduces some cache coherency issues).

Then we run the binfmt code, which will compute the final stack address. The
existing stack will be moved downwards (or upwards on PA-RISC) to the desired
place.

This 'trick' heavily relies on the MMU, so for no-MMU archs we stay with the
old approach.

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Plenty of changes all around, changes listed in the individual patches. We hope
to have addressed all issues raised.