QtAutogen tests: Rename rcconly target to camel case rccOnly.

Also add dedicated rccOnlyRes.qrc file for the rccOnly target.

Tests/QtAutogen/rccOnly.cpp

@@ -0,0 +1,9 @@
+
+extern int qInitResources_rccOnlyRes();
+
+int main(int, char**)
+{
+  // Fails to link if the symbol is not present.
+  qInitResources_rccOnlyRes();
+  return 0;
+}