Replace 'Native_capability::copy_to' by accessor

The 'copy_to' function turned out to be not flexible enough to
accommodate the Noux fork mechanism. This patch removes the function,
adds an accessor for the capability destination and a compound type
'Native_capability::Raw' to be used wherever plain capability
information must be communicated.

base-linux/include/base/platform_env.h

@@ -364,7 +364,7 @@ namespace Genode {
 			/**
 			 * Reload parent capability and reinitialize environment resources
 			 */
-			void reload_parent_cap(Capability<Parent>)
+			void reload_parent_cap(Capability<Parent>::Dst, long)
 			{
 				/* not supported on Linux */
 			}