dbusxx-xml2cpp: Only generate argument reader if there are arguments.

This shuts gcc-4.6 up about a variable being written to but not used. See
http://code.google.com/p/chromium-os/issues/detail?id=15109 for an example.

BUG=chromium-os:15109
TEST=Adhoc
Built, built cromo, built gobi-cromo-plugin.

Change-Id: I0ad5185b4f5a91b9ea7c4d5fdcfb10debcbac66b
Signed-off-by: Elly Jones <[email protected]>
Reviewed-on: http://gerrit.chromium.org/gerrit/789
Reviewed-by: Jason Glasgow <[email protected]>
diff --git a/tools/generate_adaptor.cpp b/tools/generate_adaptor.cpp
index a179ba8..ebae98f 100644
--- a/tools/generate_adaptor.cpp
+++ b/tools/generate_adaptor.cpp
@@ -408,9 +408,11 @@
 
 			body << tab << "::DBus::Message " << stub_name(method.get("name"))
 				 << "(const ::DBus::CallMessage &call)" << endl
-			<< tab << "{" << endl
-			<< tab << tab << "::DBus::MessageIter ri = call.reader();" << endl
-			<< endl;
+			<< tab << "{" << endl;
+
+			if (args_in.size() > 0)
+				body << tab << tab << "::DBus::MessageIter ri = call.reader();" << endl
+				<< endl;
 
 			body << tab << tab << "::DBus::Error error;" << endl;
 			// generate the 'in' variables