[Ada] Simplify helper units for formal hashed sets/maps

[Ada] Simplify helper units for formal hashed sets/maps

As tampering checks do not exist in formal hashed sets and maps, remove
the machinery for such checks in the version of generic key and node
operations for formal sets/maps. Update comments as well.

gcc/ada/

	* libgnat/a-chtgfk.adb (Checked_Equivalent_Keys, Checked_Index):
	Remove useless functions.
	(Delete_Key_Sans_Free, Find, Generic_Conditional_Insert): Adapt
	to removal of wrapper functions.
	* libgnat/a-chtgfk.ads (Checked_Equivalent_Keys, Checked_Index):
	Remove useless functions.
	* libgnat/a-chtgfo.adb (Checked_Index): Remove useless function.
	(Clear): Delete code commented out regarding Busy and Lock
	management.
	(Delete_Node_At_Index): Delete unused procedure.
	(Delete_Node_Sans_Free, Free, Generic_Read, Next): Adapt to
	removal of wrapper functions.
	* libgnat/a-chtgfo.ads (Checked_Index): Remove useless function.
	(Delete_Node_At_Index): Delete unused procedure.