Address data is always int64_t even if the size itself is smaller;
this was broken on bigendian hosts (still need testing!)
Create simple "write sized object" macros.
Don't combine type and size into a single argument; *every* backend
immediately breaks them apart, so it's really just a huge waste of
effort. Additionally, it avoids using short immediates in the
resulting code, which is a bad thing.
Concentrate compiler dependencies to compiler.h; make sure compiler.h
is included first in every .c file (since some prototypes may depend
on the presence of feature request macros.)
Actually use the conditional inclusion of various functions (totally
broken in previous releases.)
