[fix] Print usage info on -h/--help to libpostal cli

src/main.c

@@ -5,16 +5,31 @@
 
 #include "libpostal.h"
 #include "log/log.h"
+#include "string_utils.h"
+
+#define LIBPOSTAL_USAGE "Usage: ./libpostal address [language ...]\n"
 
 int main(int argc, char **argv) {
+    int i;
+    char *arg;
+
+    for (int i = 1; i < argc; i++) {
+        arg = argv[i];
+        if (string_equals(arg, "-h") || string_equals(arg, "--help")) {
+            printf(LIBPOSTAL_USAGE);
+            exit(EXIT_SUCCESS);
+        }
+    }
+
     if (argc < 3) {
-        log_error("Usage: test_libpostal string languages...\n");
+        log_error(LIBPOSTAL_USAGE);
         exit(EXIT_FAILURE);
     }
+
     char *str = argv[1];
     char *languages[argc - 2];
-    for (int i = 0; i < argc - 2; i++) {
-        char *arg = argv[i + 2];
+    for (i = 0; i < argc - 2; i++) {
+        arg = argv[i + 2];
         if (strlen(arg) >= MAX_LANGUAGE_LEN) {
             printf("arg %d was longer than a language code (%d chars). Make sure to quote the input string\n", i + 2, MAX_LANGUAGE_LEN - 1);
         }