Remove remnants of attempts to wrap to PHP global vars

This isn't really workable since PHP doesn't support intercepting
accesses to global variables (nor to static class properties, so
we can't wrap C/C++ global variables that way either).

The _get() and _set() function wrappers actually work and have
been generated for a very long time.

Doc/Manual/Php.html

@@ -306,8 +306,10 @@ print seki_get();
 
 <p>
 SWIG supports global variables of all C datatypes including pointers
-and complex objects.  Additional types can be supported by using the
-<tt>varinit</tt> typemap.
+and complex objects.  To support additional types, you just need to
+supply the standard <tt>in</tt> and <tt>out</tt> typemaps, which get
+used because of the wrapping as <tt>_get()</tt> and <tt>_set()</tt>
+functions.
 </p>
 
 <p>