Fix gradient regressions

1. Fix regression 8659d189 - rect. gradients no longer do grayscale

In commit 8659d189 I swapped the passing
parameters going to ImplComplexGradient and ImplLinearGradient from
aGradient (the copy) to rGradient (the original which didn't have the
grayscale applied).

2. Fix regression 954d7ad4 - grayscale applied at wrong time

In commit 954d7ad4 grayscale was applied
in DrawGradient (Rectangle &rRect...) after the gradient was written to
the metafile. I was attempting to bring it into line with what
DrawGradient (PolyPolygon &rPolyPoly...) does. However, it remains to be
seen if that's actually doing the right thing - so best to revert this
as in all likelihood I may have caused a regression with grayscaled
gradients

Change-Id: Id94549b3366adb8fcf3cddc59d30029579430a30
Reviewed-on: https://gerrit.libreoffice.org/8908Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>
Tested-by: Chris Sherlock <chris.sherlock79@gmail.com>

vcl/source/gdi/outdev4.cxx

@@ -631,17 +631,17 @@ void OutputDevice::DrawGradient( const Rectangle& rRect,
 
         Gradient aGradient( rGradient );
 
+        if ( mnDrawMode & ( DRAWMODE_GRAYGRADIENT | DRAWMODE_GHOSTEDGRADIENT ) )
+        {
+            SetGrayscaleColors( aGradient );
+        }
+
         if( mpMetaFile )
             mpMetaFile->AddAction( new MetaGradientAction( rRect, aGradient ) );
 
         if( !IsDeviceOutputNecessary() || ImplIsRecordLayout() )
             return;
 
-        if ( mnDrawMode & ( DRAWMODE_GRAYGRADIENT | DRAWMODE_GHOSTEDGRADIENT ) )
-        {
-            SetGrayscaleColors( aGradient );
-        }
-
         if ( !Rectangle( PixelToLogic( Point() ), GetOutputSize() ).IsEmpty() )
         {
             // convert rectangle to pixels
@@ -685,9 +685,9 @@ void OutputDevice::DrawGradient( const Rectangle& rRect,
                         aGradient.SetSteps( GRADIENT_DEFAULT_STEPCOUNT );
 
                     if( aGradient.GetStyle() == GradientStyle_LINEAR || aGradient.GetStyle() == GradientStyle_AXIAL )
-                        ImplDrawLinearGradient( aRect, rGradient, false, NULL );
+                        ImplDrawLinearGradient( aRect, aGradient, false, NULL );
                     else
-                        ImplDrawComplexGradient( aRect, rGradient, false, NULL );
+                        ImplDrawComplexGradient( aRect, aGradient, false, NULL );
                 }
 
                 Pop();