Move print helper functions to arg_parse.h

These functions have more to do with commands, and it will be more
helpful to have the print_help function especially in the same file as
the actual commands structure.

src/arg_parse.h

@@ -17,6 +17,8 @@
  */
 #pragma once
 
+#include <stdio.h>
+
 enum cmd_id {
 	CMD_UNKNOWN = 0,
 	CMD_HELP,
@@ -33,4 +35,23 @@ static const struct cmd commands[] = {
 	{ CMD_VERSION, {"version", "-v", "--version"} },
 };
 
+static inline void print_version(void) {
+	printf("menu-helper v%s\n\n", VERSION);
+}
+
+static inline void print_usage(void) {
+	printf("USAGE: menu-helper <cmd> [options]\n\n");
+}
+
+static inline void print_help(void) {
+	print_version();
+	print_usage();
+
+	printf("COMMANDS:\n"
+		   "\thelp, -h, --help         Show this help information.\n"
+		   "\tversion, -v, --version   Show version information.\n"
+		   "\n");
+}
+
+
 enum cmd_id parse_args(const char *cmd);

src/main.c

@@ -20,24 +20,6 @@
 
 #include "arg_parse.h"
 
-void print_version(void) {
-	printf("menu-helper v%s\n\n", VERSION);
-}
-
-void print_usage(void) {
-	printf("USAGE: menu-helper <cmd> [options]\n\n");
-}
-
-void print_help(void) {
-	print_version();
-	print_usage();
-
-	printf("COMMANDS:\n"
-		   "\thelp, -h, --help         Show this help information.\n"
-		   "\tversion, -v, --version   Show version information.\n"
-		   "\n");
-}
-
 int main(int argc, char *argv[]) {
 	enum cmd_id id;