Windows Vista/XP Styles: Remove XP-specific code

WindowsXPStyle cannot be instantiated via style factory
since 5.0. The derived class QWindowsVistaStyle still uses
much of its code, though.

Remove the XP-specific code as determined by
- Adding debug output with the enums added to WindowsXPStyle's
  functions
- Run the widgets gallery example in Vista style
- Run the widgets gallery example in XP style
- From the lines not appearing in both logs
  (comm -3), remove the code present in WindowsXPStyle

drawComplexControl() QStyle::CC_ComboBox
drawComplexControl() QStyle::CC_ScrollBar
drawComplexControl() QStyle::CC_SpinBox
drawControl() QStyle::CE_ComboBoxLabel
drawControl() QStyle::CE_HeaderSection
drawControl() QStyle::CE_ProgressBarContents
drawControl() QStyle::CE_PushButtonBevel
drawPrimitive() QStyle::PE_FrameLineEdit
drawPrimitive() QStyle::PE_IndicatorBranch
drawPrimitive() QStyle::PE_IndicatorProgressChunk
drawPrimitive() QStyle::PE_PanelItemViewItem
drawPrimitive() QStyle::PE_PanelLineEdit
sizeFromContents() QStyle::CT_SpinBox
standardIcon() QStyle::SP_CommandLink
standardPixmap() QStyle::SP_ArrowRight
standardPixmap() QStyle::SP_CommandLink
styleHint() QStyle::SH_Header_ArrowAlignment

Change-Id: Ic6a19cabf39d1089328a7cb1afdc282a60a7cf21
Reviewed-by: Oliver Wolff <[email protected]>