Improve comments about globaldb info-vectors
Fix borderline incorrect expansion of a globaldb iterator macro.

The simple form of LOOP is not supposed to contain any atoms.
Clisp rejects that and it's probably right to do so.
Fix style-warning in DEF-IR1-TRANSLATOR RETURN-FROM.

An IGNORE was getting injected not in direct relation to its binding,
but it didn't matter because the macroexpansion declares some args
ignorable anyway, for better or for worse.
Make raw slots of type SB!VM:WORD usable earlier in cold-init.
Remove unnecessary package qualifiers.
Implement CEILING/FLOOR to truncate via transforms, not inline.

CEILING/FLOOR/MOD/REM are implemented have both transforms and inline
functions, which do not play well together. The inline expansion is
applied first, causing the transforms to be ignored.
Remove duplicate floor and ceiling transforms.