gdb: hoist target_async_permitted checks into target.c

This commit moves the target_async_permitted check out of each targets
::can_async_p method and into the target_can_async_p wrapper function.

I've left some asserts in the two ::can_async_p methods that I
changed, which will hopefully catch any direct calls to these methods
that might be added in the future.

There should be no user visible changes after this commit.

1 files changed, 4 insertions, 7 deletions

diff --git a/gdb/remote.c b/gdb/remote.c
index 724386e..6ecea5b 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -14379,14 +14379,11 @@ remote_target::thread_info_to_thread_handle (struct thread_info *tp)
 bool
 remote_target::can_async_p ()
 {
-  struct remote_state *rs = get_remote_state ();
-
-  /* We don't go async if the user has explicitly prevented it with the
-     "maint set target-async" command.  */
-  if (!target_async_permitted)
-    return false;
+  /* This flag should be checked in the common target.c code.  */
+  gdb_assert (target_async_permitted);
 
-  /* We're async whenever the serial device is.  */
+  /* We're async whenever the serial device can.  */
+  struct remote_state *rs = get_remote_state ();
   return serial_can_async_p (rs->remote_desc);
 }