Trivial changes to genesis
Revise comment
Remove two obsolete exports
Improve the dumping of package tables during genesis.

- During cold-init before packages have been filled with symbols,
all symbols to be interned have their package slot set correctly.
This represents an inconsistent/impossible state normally,
but is immensely useful when examining a crash in early cold-init.

- Initial packages were intentionally oversized, but not all
of them gained additional symbols throughout the bootstrap process,
so this ended up being slightly wasteful, because resizing works
just fine, and we adjust them all again in 'save' anyway.

- The comment that "only symbols which actually have definitions ...
end up in the target packages" reflected an intent that did not
coincide with actual behavior. Extra symbols from package-data-list
affected the target. This is mostly fixed except for a hack that
assumes that every symbol in any package needed in "src/cold/warm"
is eventually needed. Notably, more than 200 symbols of SB-UNIX that
were possibly at some point manifest constants (e.g. READOWN) are
undefined and so do not appear now in the target.
Granted, package-data-list should be updated to reflect reality,
but the remainder of the problem is fixable with ease.

- *IN-PACKAGE-INIT* and *!DEFERRED-USE-PACKAGES* are eliminated.
Delete MOBY-UNINTERN, a holdover from CMUCL
Remove some imports
WITHOUT-PACKAGE-LOCKS needn't be re-invented in sb-gmp
Make package-data-list accept featureized sublists everywhere.
Dxify the lambda in PRINT-UNREADABLE-OBJECT
Fix WITH-PACKAGE-ITERATOR regression: grab vectors once and only once.
fixup NEWS for release script
1.2.3: will be tagged as "sbcl-1.2.3"
Fix binding order of supplied-p parameters in macro lambda lists.

It was done at once before all other bindings were processed, while it
should be just after the binding to which supplied-p is related is
bound.

Fixes lp#721135.