add support for a unique game identifier

A 37 character field for holding a unique identifier is added
to the save file, as well as to an ancestor field in bones files.

Since it requires installation of libuuid package on Linux,
it requires an exlicit WANT_NHUUID=1 on the Make command line there.
Without the libuuid support, the saved nhuuid is empty, which should
be harmless.

This also moves the save and restore of gm.moves higher up so that it
already has a value the first time it is used against a relative saved
timestamp.

Invalidates savefiles and bones files due to new fields.

I need to get this committed before I can test out the macOS portion,
so there may be some build issues there briefly (hopefully), and
follow-up commits to resolve them.

Increments EDITLEVEL.

sys/windows/windsys.c

@@ -28,6 +28,7 @@
 #include <errno.h>
 
 #ifdef WIN32
+#include <rpc.h>
 #include <VersionHelpers.h>
 #include <UserEnv.h>
 
@@ -530,6 +531,36 @@ nethack_exit(int code)
     exit(code);
 }
 
+void
+get_nhuuid(void)
+{
+    UUID binuuid;
+    unsigned char *stmp;
+    RPC_STATUS rpcstatus;
+
+    if (svn.nhuuid[0])
+        return;
+
+    rpcstatus = UuidCreate(&binuuid);
+    if (rpcstatus == RPC_S_OK) {
+        rpcstatus = UuidToStringA(&binuuid, &stmp);
+        if (rpcstatus == RPC_S_OK) {
+            Snprintf(svn.nhuuid, sizeof svn.nhuuid, "%s", (char *) stmp);
+            RpcStringFree(&stmp);
+        }
+    }
+}
+
+void
+free_nhuuid(void)
+{
+    int i;
+
+    for (i = 0; i < SIZE(svn.nhuuid); i++) {
+        svn.nhuuid[i] = 0;
+    }
+}
+
 #ifdef WIN32CON
 #undef kbhit
 #include <conio.h>