Detect library name clashes.

libsolidity/interface/CompilerStack.h

@@ -199,6 +199,9 @@ private:
 	};
 
 	void resolveImports();
+	/// Checks whether there are libraries with the same name, reports that as an error and
+	/// @returns false in this case.
+	bool checkLibraryNameClashes();
 	/// @returns the absolute path corresponding to @a _path relative to @a _reference.
 	std::string absolutePath(std::string const& _path, std::string const& _reference) const;
 	/// Compile a single contract and put the result in @a _compiledContracts.