Added decl_early_init() which is called when PLAYAGAIN is supported.

decl_early_init() is called when we are starting a game.  On first
start, it validates that global state is in the expected state.
When called on subsequent starts, it initializes global state to
expected state.

sys/share/pcmain.c

@@ -97,7 +97,11 @@ char *argv[];
 
     nethack_enter(argc, argv);
 
+#ifdef PLAYAGAIN
+    decl_early_init();
+#endif
     sys_early_init();
+
 #if defined(WIN32) && defined(TTY_GRAPHICS)
     Strcpy(default_window_sys, "tty");
 #else

sys/winnt/stubs.c

@@ -37,6 +37,9 @@ char *argv[];
 {
     boolean resuming;
 
+#ifdef PLAYAGAIN
+    decl_early_init();
+#endif
     sys_early_init();
     Strcpy(default_window_sys, "tty");
     resuming = pcmain(argc, argv);