include: Added msftedit support in richedit.h.

include/richedit.h

@@ -32,6 +32,14 @@ extern "C" {
 
 #define cchTextLimitDefault 0x7fff
 
+#if defined(__GNUC__)
+# define MSFTEDIT_CLASS (const WCHAR []){ 'R','i','c','h','E','d','i','t','5','0','W',0 }
+#elif defined(_MSC_VER)
+# define MSFTEDIT_CLASS L"RichEdit50W"
+#else
+static const WCHAR MSFTEDIT_CLASS[] = { 'R','i','c','h','E','d','i','t','5','0','W',0 };
+#endif
+
 #define RICHEDIT_CLASS20A	"RichEdit20A"
 #if defined(__GNUC__)
 # define RICHEDIT_CLASS20W (const WCHAR []){ 'R','i','c','h','E','d','i','t','2','0','W',0 }