PyUtils: cling bug workaround.

When we run aclic, root produces a DSO and tries to link it. As past of this, ROOT tries to find all the libraries that the new DSO depends on by listing all its symbols and then walking through all libraries on LD_LIBRARY_PATH to find a definition. Due to a bug, cling will crash if it encounters a separate-debug library in doing so. Pretty much every library contains the gprof stub gmon_start as a hidden weak symbol. Cling ends up searching for this symbol, and since it is hidden, it will end up trying all libraries. In Athena builds, it eventually hits a debug library and dies.

Work around by injecting a dummy defintion of gmon_start.

Fixes unit test failure in master.