Stop execution when performing HIO request

Since the HIO request is basically treated like a syscall, we need to
stop emulation while waiting for the GDB client to reply with the
result. This ensures any memory queries etc. that GDB makes to fulfill
the HIO request are accessing memory as it was at the time of the
request, instead of afterwards.

src/core/gdbstub/hio.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <string>
+
 #include "common/common_types.h"
 
 namespace GDBStub {
@@ -29,7 +31,9 @@ void SetHioRequest(const VAddr address);
 
 bool HandleHioReply(const u8* const command_buffer, const u32 command_length);
 
-bool HasHioRequest();
+bool HasPendingHioRequest();
+
+bool WaitingForHioReply();
 
 std::string BuildHioRequestPacket();