Include common attachment preparation in both core targets

src/Makefile.am

@@ -69,6 +69,8 @@ utun_CORE_SOURCES = \
 	media_async/attachment.h \
 	media_async/voice_file.c \
 	media_async/voice_file.h \
+	media_async/attachment_send.c \
+	media_async/attachment_send.h \
 	video/video.c \
 	transport_layer/dummynet.c \
 	ntp_time.c \
@@ -185,6 +187,8 @@ libutun_a_SOURCES = \
 	media_async/attachment.h \
 	media_async/voice_file.c \
 	media_async/voice_file.h \
+	media_async/attachment_send.c \
+	media_async/attachment_send.h \
 	video/video.c \
 	transport_layer/dummynet.c \
 	ntp_time.c \

src/media_async/attachment_send.c

@@ -115,7 +115,7 @@ static void attachment_prepare_done(void* arg, int error) {
 void attachment_send_trampoline(void* arg) {
     struct attachment_send_req* req = arg;
     if (!req) return;
-    if (!req->inst || !req->inst->chat || !req->inst->media_async || !req->target[0] ||
+    if (!req->inst || !req->inst->chat_core || !req->inst->media_async || !req->target[0] ||
         strspn(req->target, "0123456789") != strlen(req->target)) {
         DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "attachment: invalid target/stopped service");
         attachment_release_pcm(req); u_free(req); return;