WIN rename SalFrames SalGraphics pointers

This renames mpGraphics => mpLocalGraphics and mpGraphics2 to
mpThreadGraphics.

Change-Id: I649b956abc9587f1be74872d439fefc5f5b21135
Reviewed-on: https://gerrit.libreoffice.org/50907Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

vcl/inc/win/salframe.h

@@ -33,8 +33,8 @@ public:
     HWND                    mhWnd;                  // Window handle
     HCURSOR                 mhCursor;               // cursor handle
     HIMC                    mhDefIMEContext;        // default IME-Context
-    WinSalGraphics*         mpGraphics;             // current frame graphics
-    WinSalGraphics*         mpGraphics2;            // current frame graphics for other threads
+    WinSalGraphics*         mpLocalGraphics;        // current local frame graphics
+    WinSalGraphics*         mpThreadGraphics;       // current frame graphics for other threads
     WinSalFrame*            mpNextFrame;            // pointer to next frame
     HMENU                   mSelectedhMenu;         // the menu where highlighting is currently going on
     HMENU                   mLastActivatedhMenu;    // the menu that was most recently opened