Remove globals/make jq_init/next/teardown() an API

main.c

@@ -63,9 +63,10 @@ static int options = 0;
 static struct bytecode* bc;
 
 static void process(jv value) {
-  jq_init(bc, value);
+  jq_state *jq = NULL;
+  jq_init(bc, value, &jq);
   jv result;
-  while (jv_is_valid(result = jq_next())) {
+  while (jv_is_valid(result = jq_next(jq))) {
     if ((options & RAW_OUTPUT) && jv_get_kind(result) == JV_KIND_STRING) {
       fwrite(jv_string_value(result), 1, jv_string_length(jv_copy(result)), stdout);
       jv_free(result);
@@ -85,7 +86,7 @@ static void process(jv value) {
     printf("\n");
   }
   jv_free(result);
-  jq_teardown();
+  jq_teardown(&jq);
 }
 
 static jv slurp_file(const char* filename) {