Partially fix compilation problem on Mac OSX and gcc/4.10.0 #322

This fixes the issue referenced in Issue #322. However, now compilation of libmesh with g++-4.10.0 fails with the following error message:

    src/mesh/gmsh_io.C:1097:1: internal compiler error: in insn_default_length, at config/i386/i386.md:1787

    src/mesh/gmsh_io.C:1097:1: internal compiler error: Abort trap: 6
    g++: internal compiler error: Abort trap: 6 (program cc1plus)

However, this is a [known issue](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61387), so presumably we can just wait for this problem to fix itself.