winedbg: Store for context variables only the offsets of each register (instead of the address of the register in dbg_context).

dbghelp: Extend the CPU object in order to manipulate context's registers (getting context's content & register names).

dbghelp: Keep the .debug_frame section mapped when parsing dwarf debug_info (needed for CFA management).

wined3d: Add support for partial updates of compressed surfaces to IWineD3DDeviceImpl_UpdateSurface().