Remove ill-advised cygwin_props

Cygwin_props have been invented to allow switching off the unique
installation keys in the first place, supposedly for debugging.
This never really was a good idea, after all we *want* the installations
to be independent and there's no good reason to break that, not even
for debugging purposes.

Other than that, cygwin_props were meant to be used for some other global
settings which never took place.  There's just no good reason to tweak
the DLL binary invisibly where a setting could be done in a file or the
environment.

This patch removes the cygwin_props entirely, including the related
settings in cygcheck.

cygwin:
	* cygprops.h: Remove file.
	* globals.cc (cygwin_props): Remove.
	* cygheap.cc (init_cygheap::init_installation_root): Drop removing
	installation key.

utils:
	* cygcheck.cc: Drop including cygprops.h.  Remove now unused option
	values.
	(unique_object_name_opt): Remove.
	(handle_unique_object_name): Remove function.
	(usage): Remove text for unique-object-names options.
	(longopts): Remove unique-object-names options.
	(main): Drop handling unique-object-names options.

doc:
	* utils.xml (cygcheck): Remove text for unique-object-names options.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/cygheap.cc

@@ -219,12 +219,6 @@ init_cygheap::init_installation_root ()
 				    installation_root)))
 	break;
     }
-
-  if (cygwin_props.disable_key)
-    {
-      installation_key.Length = 0;
-      installation_key.Buffer[0] = L'\0';
-    }
 }
 
 void __stdcall