WinCon: define all of PDC_WIDE, UNICODE, _UNICODE if one of those are…

… defined

Per MSDN one should always define both macros, as they are used in different contexts, but must match.
The definition of `UNICODE` can also be provided by the build environment, especially with MSVC, in which case PDC_WIDE must be defined as well.

wincon/pdcwin.h

@@ -12,8 +12,16 @@
    #define PDC_WIDE
 #endif
 
-#if defined(PDC_WIDE) && !defined(UNICODE)
-# define UNICODE
+#if defined( PDC_WIDE) || defined( UNICODE) || defined( _UNICODE)
+   #if !defined( PDC_WIDE)
+      # define PDC_WIDE
+   #endif
+   #if !defined( UNICODE)
+      # define UNICODE
+   #endif
+   #if !defined( _UNICODE)
+      # define _UNICODE
+   #endif
 #endif
 
 #define WIN32_LEAN_AND_MEAN