monitor: Fix do_wav_capture() argument type

Currently do_wav_capture() path's argument type is 's' (string),
but it should be 'F' (filename), this way 'wavcapture' gets
command completion.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

qemu-monitor.hx

@@ -402,7 +402,7 @@ info mice
 ETEXI
 
 #ifdef HAS_AUDIO
-    { "wavcapture", "path:s,freq:i?,bits:i?,nchannels:i?", do_wav_capture,
+    { "wavcapture", "path:F,freq:i?,bits:i?,nchannels:i?", do_wav_capture,
       "path [frequency [bits [channels]]]",
       "capture audio to a wave file (default frequency=44100 bits=16 channels=2)" },
 #endif