add setlocale() (mostly for datetime function)

slstatus.c

@@ -6,6 +6,7 @@
 #include <ifaddrs.h>
 #include <limits.h>
 #include <linux/wireless.h>
+#include <locale.h>
 #include <netdb.h>
 #include <pwd.h>
 #include <signal.h>
@@ -634,6 +635,8 @@ main(int argc, char *argv[])
 		dpy = XOpenDisplay(NULL);
 	}
 
+	setlocale(LC_ALL, "");
+
 	while (!done) {
 		status_string[0] = '\0';