Fix D-Bus marshalling of booleans in optimised code.

C++ booleans are 1 byte in size, but D-Bus booleans (dbus_bool_t) are
4 bytes. That means a boolean with a zero in the LSB byte but non-zero
garbage in the high bytes is a valid "false" in C++, but libdbus-1
will turn that to true when sending.

Task-number: QTBUG-7041
Reviewed-By: Trust Me
BT: yes

Author: Thiago Macieira

src/dbus/qdbusmarshaller.cpp

@@ -378,7 +378,6 @@ bool QDBusMarshaller::appendVariantInternal(const QVariant &arg)
     switch (*signature) {
 #ifdef __OPTIMIZE__
     case DBUS_TYPE_BYTE:
-    case DBUS_TYPE_BOOLEAN:
     case DBUS_TYPE_INT16:
     case DBUS_TYPE_UINT16:
     case DBUS_TYPE_INT32:
@@ -388,6 +387,9 @@ bool QDBusMarshaller::appendVariantInternal(const QVariant &arg)
     case DBUS_TYPE_DOUBLE:
         qIterAppend(&iterator, ba, *signature, arg.constData());
         return true;
+    case DBUS_TYPE_BOOLEAN:
+        append( arg.toBool() );
+        return true;
 #else
     case DBUS_TYPE_BYTE:
         append( qvariant_cast<uchar>(arg) );