perf debug: Move dump_stack() and sighandler_dump_stack() to debug.h

Two more out of util.h.

Link: http://lkml.kernel.org/n/tip-polkuxm1cpr06lbgue5pyqum@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/debug.h

@@ -56,4 +56,7 @@ int perf_debug_option(const char *str);
 void perf_debug_setup(void);
 int perf_quiet_option(void);
 
+void dump_stack(void);
+void sighandler_dump_stack(int sig);
+
 #endif	/* __PERF_DEBUG_H */