gcc 4.4 is not happy with sleap's boost source

If by any chance you are using gcc 4.4 to compile sleap under gleap directory, you might encounter problems like this error:

../../ext/boost/mpl/apply_wrap.hpp:81:31: error: missing binary operator before token "("
../../ext/boost/mpl/apply_wrap.hpp:173:31: error: missing binary operator before token "("
....

This is due to some behaviors changes after gcc 4.4 that interpret C preprocessing macro differently. Here is a patch to workaround. We might need to use newer boost for or system's boost lib.