valgrind fails with boost::math::erfc_inv<long double>(long double, long double): Overflow Error

When running 'mongod' under valgrind, the process immediately hits an exception while executing global initializers.
This is due to a bad interaction between Boost and Valgrind, where Valgrind does not fully support long doubles.

To work around this, use CPPDEFINES=BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS when compiling.

See https://svn.boost.org/trac/boost/ticket/10005