Try this instead of changing the code:
1. Add "txml" to the library list and place it before the codeblocks library.
2. Add the "txml" dir (...\sdk\tinyxml) to the library dirs (I placed it first, but don't think it matters).
For some reason, when the make for the SDK DLL creates the static lib ("Create static library too" is checked), it doesn't link in libtxml.a in its original form. Any ideas?