fix incorrect overload error in different namespaces with same suffix

===
namespace a {
    fun f() = 1
}

namespace b {
    namespace a {
        fun f() = 1
    }
}
===

compiler/frontend/src/org/jetbrains/jet/lang/resolve/OverloadResolver.java

@@ -8,6 +8,7 @@ import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.diagnostics.Errors;
 import org.jetbrains.jet.lang.psi.*;
+import org.jetbrains.jet.resolve.DescriptorRenderer;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -61,7 +62,7 @@ public class OverloadResolver {
             DeclarationDescriptor containingDeclaration = function.getContainingDeclaration();
             if (containingDeclaration instanceof NamespaceDescriptor) {
                 NamespaceDescriptor namespaceDescriptor = (NamespaceDescriptor) containingDeclaration;
-                functionsByName.putValue(new Key(namespaceDescriptor.getName(), function.getName()), function);
+                functionsByName.putValue(new Key(DescriptorRenderer.getFQName(namespaceDescriptor), function.getName()), function);
             }
         }
 

compiler/testData/checkerWithErrorTypes/quick/ConflictingOverloads.jet

@@ -40,3 +40,9 @@ namespace ns2 {
     fun e() = 1
 }
 
+namespace ns3 {
+    namespace ns1 {
+        fun e() = 1
+    }
+}
+