- add BB_APPLET_RUNLEVEL used by emdebian via /etc/init.d/rc.

Note that we leave the buggy CONFIG_* namespace now, so please fix any applet you thouch.

include/applets.h

@@ -565,6 +565,9 @@
 #ifdef CONFIG_RUN_PARTS
 	APPLET_ODDNAME("run-parts", run_parts_main, _BB_DIR_BIN, _BB_SUID_NEVER, run_parts)
 #endif
+#if BB_APPLET_RUNLEVEL
+	APPLET(runlevel, runlevel_main, _BB_DIR_SBIN, _BB_SUID_NEVER)
+#endif
 #ifdef CONFIG_RX
 	APPLET(rx, rx_main, _BB_DIR_USR_BIN, _BB_SUID_NEVER)
 #endif

include/usage.h

@@ -2450,6 +2450,18 @@
 	"\t-a ARG\tPass ARG as an argument for every program invoked\n" \
 	"\t-u MASK\tSet the umask to MASK before executing every program"
 
+#if BB_APPLET_RUNLEVEL
+#define runlevel_trivial_usage \
+	"[utmp]"
+#define runlevel_full_usage \
+	"Find the current and previous system runlevel.\n\n" \
+	"If no utmp file exists or if no runlevel record can be found,\n" \
+	"runlevel prints \"unknown\""
+#define runlevel_example_usage \
+	"$ runlevel /var/run/utmp\n" \
+	"N 2"
+#endif
+
 #define rx_trivial_usage \
 	"FILE"
 #define rx_full_usage \