use syswrite instead of print for sending sysrq

to avoid buffering inside of perl

build-vm-kvm

@@ -376,7 +376,7 @@ vm_cleanup_kvm() {
 vm_sysrq_kvm() {
     perl -e 'use Socket; socket(SOCK, PF_UNIX, SOCK_STREAM, 0) || die("socket: $!\n"); 
              connect(SOCK, sockaddr_un("'"$VM_ROOT.qemu/monitor"'")) || die("connect: $!\n");
-             print SOCK "sendkey alt-print-'$1'\n";'
+             syswrite SOCK "sendkey alt-print-'$1'\n";'
 }
 
 vm_wipe_kvm() {