gdb/infcmd: remove redundant clear_proceed_status call

In `attach_command`, there is a call to `init_wait_for_inferior`
followed by a call to `clear_proceed_status`.  However,
`init_wait_for_inferior` already calls `clear_proceed_status`.  Remove
the redundant call.

Regression-tested on X86_64 Linux.

gdb/ChangeLog:
2020-10-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* infcmd.c (attach_command): Remove the redundant call to
	`clear_proceed_status`.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2020-10-07  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>
+
+	* infcmd.c (attach_command): Remove the redundant call to
+	`clear_proceed_status`.
+
 2020-10-07  Kamil Rytarowski  <n54@gmx.com>
 
 	* nat/netbsd-nat.c (write_memory, read_memory): Update.

gdb/infcmd.c

@@ -2619,7 +2619,6 @@ attach_command (const char *args, int from_tty)
   /* Set up execution context to know that we should return from
      wait_for_inferior as soon as the target reports a stop.  */
   init_wait_for_inferior ();
-  clear_proceed_status (0);
 
   inferior->needs_setup = 1;