kconfig: fix segfault when detecting recursive dependency

Following sample Kconfig generated a segfault:

config FOO
        bool
        select PERF_EVENTS if HAVE_HW_BREAKPOINT

config PERF_EVENTS
        bool

config HAVE_HW_BREAKPOINT
        bool
        depends on PERF_EVENTS

Fix by reverting back to a valid property if there was no
property on the stack of symbols.

The above pattern were seen in sh Kconfig.
A fix for the Kconfig file has been sent to the sh folks.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/kconfig/symbol.c

@@ -937,6 +937,8 @@ static void sym_check_print_recursive(struct symbol *last_sym)
 		sym = stack->sym;
 		next_sym = stack->next ? stack->next->sym : last_sym;
 		prop = stack->prop;
+		if (prop == NULL)
+			prop = stack->sym->prop;
 
 		/* for choice values find the menu entry (used below) */
 		if (sym_is_choice(sym) || sym_is_choice_value(sym)) {