Standardize version output

Changes:

* Only print the version line in the print_version function
* Add a print_version function where missing (put it in usage.c if the
  file exists)
* Always a blank line after the version

src/firecfg/main.c

@@ -59,11 +59,14 @@ static char *usage_str =
 	"License GPL version 2 or later\n"
 	"Homepage: https://firejail.wordpress.com\n\n";
 
-static void usage(void) {
+static void print_version(void) {
 	printf("firecfg version %s\n\n", VERSION);
-	puts(usage_str);
 }
 
+static void usage(void) {
+	print_version();
+	puts(usage_str);
+}
 
 static void list(void) {
 	DIR *dir = opendir(arg_bindir);
@@ -364,7 +367,7 @@ int main(int argc, char **argv) {
 		else if (strcmp(argv[i], "--debug") == 0)
 			arg_debug = 1;
 		else if (strcmp(argv[i], "--version") == 0) {
-			printf("firecfg version %s\n\n", VERSION);
+			print_version();
 			return 0;
 		}
 		else if (strcmp(argv[i], "--clean") == 0) {

src/firemon/firemon.c

@@ -145,7 +145,7 @@ int main(int argc, char **argv) {
 			return 0;
 		}
 		else if (strcmp(argv[i], "--version") == 0) {
-			printf("firemon version %s\n\n", VERSION);
+			print_version();
 			return 0;
 		}
 		else if (strcmp(argv[i], "--debug") == 0)

src/firemon/firemon.h

@@ -49,6 +49,7 @@ void firemon_sleep(int st);
 void procevent(pid_t pid) __attribute__((noreturn));
 
 // usage.c
+void print_version(void);
 void usage(void);
 
 // top.c

src/firemon/usage.c

@@ -78,7 +78,11 @@ static char *help_str =
 	"Homepage: https://firejail.wordpress.com\n"
 	"\n";
 
+void print_version(void) {
+	printf("firemon version %s\n\n", VERSION);
+}
+
 void usage(void) {
-	printf("firemon version %s\n", VERSION);
+	print_version();
 	puts(help_str);
 }

src/jailcheck/main.c

@@ -36,9 +36,12 @@ static char *usage_str =
 	"   --help, -? - this help screen.\n"
 	"   --version - print program version and exit.\n";
 
+static void print_version(void) {
+	printf("jailcheck version %s\n\n", VERSION);
+}
 
 static void usage(void) {
-	printf("jailcheck version %s\n\n", VERSION);
+	print_version();
 	puts(usage_str);
 }
 
@@ -62,7 +65,7 @@ int main(int argc, char **argv) {
 			return 0;
 		}
 		else if (strcmp(argv[i], "--version") == 0) {
-			printf("firetest version %s\n\n", VERSION);
+			print_version();
 			return 0;
 		}
 		else if (strncmp(argv[i], "--hello=", 8) == 0) { // used by noexec test