Better fix for 32 bit wxOSX build

Instead of disabling vertical alignment support in wxDataViewCtrl, move the
private variables to the header file: this is supported by all versions of the
Objective-C runtime, including the old one used for 32 bit applications,
unlike the new way based on declaring the variable in an anonymous extension.

This replaces the changes of 22216b70e7.

include/wx/osx/cocoa/dataview.h

@@ -376,6 +376,12 @@ private:
     #define wxTextFieldCell NSTextFieldCell
 #else
 @interface wxTextFieldCell : NSTextFieldCell
+{
+@private
+    int _wxAlignment;
+    BOOL _adjustRect;
+}
+
     -(void) setWXAlignment:(int)alignment;
 @end
 #endif

src/osx/cocoa/dataview.mm

@@ -1252,20 +1252,6 @@ outlineView:(NSOutlineView*)outlineView
 // wxTextFieldCell
 // ============================================================================
 
-#ifndef _LP64
-    // The code below doesn't compile in 32 bits failing with
-    //
-    //      error: instance variables may not be placed in class extension
-    //
-    // Until this can be fixed, disable it to at least fix compilation.
-#else
-@interface wxTextFieldCell ()
-{
-    int _wxAlignment;
-    BOOL _adjustRect;
-}
-@end
-
 @implementation wxTextFieldCell
 
 - (void)setWXAlignment:(int)alignment
@@ -1331,7 +1317,6 @@ outlineView:(NSOutlineView*)outlineView
 }
 
 @end
-#endif // 32/64 bits
 
 
 // ============================================================================
@@ -2763,10 +2748,8 @@ void wxDataViewRenderer::OSXUpdateAlignment()
     int align = GetEffectiveAlignment();
     NSCell *cell = GetNativeData()->GetColumnCell();
     [cell setAlignment:ConvertToNativeHorizontalTextAlignment(align)];
-#ifdef _LP64
     if ([cell respondsToSelector:@selector(setWXAlignment:)])
         [(wxTextFieldCell*)cell setWXAlignment:align];
-#endif // _LP64
 }
 
 void wxDataViewRenderer::SetMode(wxDataViewCellMode mode)