Extract usage information into a separate file.

dmesg.c

@@ -32,16 +32,6 @@ static inline _syscall3(int, klogctl, int, type, char *, b, int, len);
 # include <sys/klog.h>
 #endif
 
-static const char dmesg_usage[] = "dmesg [-c] [-n LEVEL] [-s SIZE]\n"
-#ifndef BB_FEATURE_TRIVIAL_HELP
-	"\nPrints or controls the kernel ring buffer\n\n"
-	"Options:\n"
-	"\t-c\t\tClears the ring buffer's contents after printing\n"
-	"\t-n LEVEL\tSets console logging level\n"
-	"\t-s SIZE\t\tUse a buffer of size SIZE\n"
-#endif
-	;
-
 int dmesg_main(int argc, char **argv)
 {
 	char *buf, c;