qemu-kvm: Don't try to init KVM during libvirt introspection

If it's disabled on the host, libvirt logs a ton of errors to
syslog.

qemu-kvm.sh

@@ -1,3 +1,10 @@
 #!/bin/sh
 
-exec /usr/bin/qemu-system-x86_64 -machine accel=kvm "$@"
+# Libvirt introspects the binary using -M none. In that case, don't try
+# to init KVM, which will fail and be noisy if the host has kvm disabled
+opts="-machine accel=kvm"
+if echo "$@" | grep -q " -M none "; then
+    opts=
+fi
+
+exec /usr/bin/qemu-system-x86_64 $opts "$@"