qemu-user not responding to Ctrl-C from gdb
Description of problem:
When attached to qemu-x84_64's gdbserver via gdb, it is not possible to interrupt the binary being emulated. Usually, Ctrl-C will interrupt a running binary from gdb and I believe (though have not tested) it works in qemu-system.

First Ctrl-C will do nothing and second will prompt to stop debugging.
```
(gdb) c
Continuing.
^C^CThe target is not responding to interrupt requests.
Stop debugging it? (y or n)
```
Steps to reproduce:
1. Run `./qemu-x86_64 -g 1234 ~/Downloads/base64-x64_64-static` or any static binary that will pause/hang
2. Connect from gdb `(gdb) target remote :1234`
3. Ctrl-C in gdb