global: add client API pointer to library handle

Makes the next commit simpler. It's probably a bad idea to add more
fields to the global state, but on the other hand the client API state
is pretty much per-instance anyway. It also will help with things like
the proposed libmpv custom stream API.

common/global.h

@@ -7,6 +7,7 @@
 struct mpv_global {
     struct MPOpts *opts;
     struct mp_log *log;
+    struct mp_client_api *client_api;
 };
 
 #endif

player/client.c

@@ -21,6 +21,7 @@
 #include <assert.h>
 
 #include "common/common.h"
+#include "common/global.h"
 #include "common/msg.h"
 #include "common/msg_control.h"
 #include "input/input.h"
@@ -137,6 +138,7 @@ void mp_clients_init(struct MPContext *mpctx)
     *mpctx->clients = (struct mp_client_api) {
         .mpctx = mpctx,
     };
+    mpctx->global->client_api = mpctx->clients;
     pthread_mutex_init(&mpctx->clients->lock, NULL);
 }
 
@@ -264,6 +266,11 @@ struct MPContext *mp_client_get_core(struct mpv_handle *ctx)
     return ctx->mpctx;
 }
 
+struct MPContext *mp_client_api_get_core(struct mp_client_api *api)
+{
+    return api->mpctx;
+}
+
 static void wakeup_client(struct mpv_handle *ctx)
 {
     pthread_mutex_lock(&ctx->wakeup_lock);

player/client.h

@@ -31,6 +31,7 @@ void mp_client_property_change(struct MPContext *mpctx, const char *name);
 struct mpv_handle *mp_new_client(struct mp_client_api *clients, const char *name);
 struct mp_log *mp_client_get_log(struct mpv_handle *ctx);
 struct MPContext *mp_client_get_core(struct mpv_handle *ctx);
+struct MPContext *mp_client_api_get_core(struct mp_client_api *api);
 
 void mp_resume_all(struct mpv_handle *ctx);
 

player/misc.c

@@ -250,6 +250,7 @@ struct mpv_global *create_sub_global(struct MPContext *mpctx)
     *new = (struct mpv_global){
         .log = mpctx->global->log,
         .opts = new_config->optstruct,
+        .client_api = mpctx->clients,
     };
     return new;
 }