Simplify DLL hook mechanism

This change deletes the GetProcAddress hook and exports symbols
corresponding to the hooked functions from each hook DLL instead;
we stop at redirecting LoadLibrary/GetModuleHandle calls to the
hook DLL. This simplified approach has less hidden magic going on
behind the scenes and is more readily composable (i.e. a hook DLL
can export redirect symbols for more than one dynamically-loaded
DLL).

idzhook/idzhook.def

@@ -1 +1,8 @@
 LIBRARY idzhook
+
+EXPORTS
+    Direct3DCreate9
+    amDllVideoClose @2
+    amDllVideoGetVBiosVersion @4
+    amDllVideoOpen @1
+    amDllVideoSetResolution @3