node: move a mpv_node helper from ipc.c to shared code

This particular one is needed in a following commit.

input/ipc.c

@@ -20,23 +20,12 @@
 #include "common/msg.h"
 #include "input/input.h"
 #include "misc/json.h"
+#include "misc/node.h"
 #include "options/m_option.h"
 #include "options/options.h"
 #include "options/path.h"
 #include "player/client.h"
 
-static mpv_node *mpv_node_map_get(mpv_node *src, const char *key)
-{
-    if (src->format != MPV_FORMAT_NODE_MAP)
-        return NULL;
-
-    for (int i = 0; i < src->u.list->num; i++)
-        if (!strcmp(key, src->u.list->keys[i]))
-            return &src->u.list->values[i];
-
-    return NULL;
-}
-
 static mpv_node *mpv_node_array_get(mpv_node *src, int index)
 {
     if (src->format != MPV_FORMAT_NODE_ARRAY)
@@ -217,9 +206,9 @@ static char *json_execute_command(struct mpv_handle *client, void *ta_parent,
         goto error;
     }
 
-    reqid_node = mpv_node_map_get(&msg_node, "request_id");
+    reqid_node = node_map_get(&msg_node, "request_id");
 
-    mpv_node *cmd_node = mpv_node_map_get(&msg_node, "command");
+    mpv_node *cmd_node = node_map_get(&msg_node, "command");
     if (!cmd_node ||
         (cmd_node->format != MPV_FORMAT_NODE_ARRAY) ||
         !cmd_node->u.list->num)

misc/node.c

@@ -81,3 +81,16 @@ void node_map_add_flag(struct mpv_node *dst, const char *key, bool v)
 {
     node_map_add(dst, key, MPV_FORMAT_FLAG)->u.flag = v;
 }
+
+mpv_node *node_map_get(mpv_node *src, const char *key)
+{
+    if (src->format != MPV_FORMAT_NODE_MAP)
+        return NULL;
+
+    for (int i = 0; i < src->u.list->num; i++) {
+        if (strcmp(key, src->u.list->keys[i]) == 0)
+            return &src->u.list->values[i];
+    }
+
+    return NULL;
+}

misc/node.h

@@ -10,5 +10,6 @@ void node_map_add_string(struct mpv_node *dst, const char *key, const char *val)
 void node_map_add_int64(struct mpv_node *dst, const char *key, int64_t v);
 void node_map_add_double(struct mpv_node *dst, const char *key, double v);
 void node_map_add_flag(struct mpv_node *dst, const char *key, bool v);
+mpv_node *node_map_get(mpv_node *src, const char *key);
 
 #endif