api/nvim_get_mode: Use child-queue instead of "priority".

src/nvim/msgpack_rpc/channel.h

@@ -11,6 +11,11 @@
 
 #define METHOD_MAXLEN 512
 
+/// HACK: os/input.c drains this queue immediately before blocking for input.
+///       Events on this queue are async-safe, but they need the resolved state
+///       of os_inchar(), so they are processed "just-in-time".
+MultiQueue *ch_before_blocking_events;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "msgpack_rpc/channel.h.generated.h"
 #endif