Revert "sc tiled rendering: We keep increasing the precision here..."

This reverts commit 27ca6387, at least together
with f7962f59 "sc rowlimit: Make the cursor
better fit the rendering" it makes CppunitTest_desktop_lib fail.

sc/source/core/data/global.cxx

@@ -519,9 +519,9 @@ void ScGlobal::Init()
 void ScGlobal::InitPPT()
 {
     OutputDevice* pDev = Application::GetDefaultDevice();
-
-    nScreenPPTX = double(pDev->GetDPIX()) / double(TWIPS_PER_INCH);
-    nScreenPPTY = double(pDev->GetDPIY()) / double(TWIPS_PER_INCH);
+    Point aPix1000 = pDev->LogicToPixel( Point(100000,100000), MapUnit::MapTwip );
+    nScreenPPTX = aPix1000.X() / 100000.0;
+    nScreenPPTY = aPix1000.Y() / 100000.0;
 }
 
 const OUString& ScGlobal::GetClipDocName()