Carbonate:  Make {CreateNew,Dispose}Port() extern

Move the definitions of CreateNewPort() and DisposePort() out-of-header,
since they're not small enough to warrant inlining.  Declare them in the
header whenever ACCESSOR_CALLS_ARE_FUNCTIONS is false (since they're not
declared in Quickdraw.h in that case) and define them only on 68K, which
doesn't have CarbonAccessors.o.
Carbonate:  Compile Carbon accessors on PPC also

Instead of linking against CarbonAccessors.o on PPC, reuse the functions
we already wrote for use with 68K (if ACCESSOR_CALLS_ARE_FUNCTIONS isn't
set).  (Suppress the new link warnings since we haven't actually trashed
CarbonAccessors.o yet.)

This is necessary to unset ACCESSOR_CALLS_ARE_FUNCTIONS:  If we had just
unset it, we'd get a linker warning complaining that GetNextWindow() was
redefined in CarbonAccessors.o (though I haven't the slightest idea how,
since the other definition is inline).  If we jettison CarbonAccessors.o
on the other hand, we'll need definitions of any functions which are now
68K-only.  As a bonus, this eliminates the nuisance of CodeWarrior IDE's
irritating "This source file contains null characters.  Are you sure you
want to open it?" alert *and* lets you actually step into source code in
the debugger.
A-line:  Don't define ACCESSOR_CALLS_ARE_FUNCTIONS

This yields a warning for redefining GetNextWindow(), which is an inline
in MacWindows.h.  Since it can show up in any file, this doesn't seem to
be avoidable without either (a) revising the way the link warning filter
works or (b) not linking against CarbonAccessors.o.  (We'll choose (b).)
Merge branch 'accessor-calls'