emscripten builds need BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS

[NickelWenzel]

Using boost::math when compiling to wasm32 via emscripten is not possible out of the box right now because BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS is not defined.

It seems like this is a regression that was introduced by the following PR #753 which seems to be related to #728 and #729.

@jzmaddock to me it looks like uncommenting the define in config.hpp

#if (defined(__NetBSD__) || defined(__EMSCRIPTEN__)\
   || (defined(__hppa) && !defined(__OpenBSD__)) || (defined(__NO_LONG_DOUBLE_MATH) && (DBL_MANT_DIG != LDBL_MANT_DIG))) \
   && !defined(BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS)
//#  define BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS
#endif`

would solve the problem and i'd happily prepare a PR if you see no negative consequences for NetBSD and hppa since they would also get affected by this change.

[mborland]

I would recommend making a PR that only affects your platform. We do not have NetBSD in the CI nor do we have hppa since it requires specific hardware.

[NickelWenzel]

Thanks for getting back so swiftly :) I did that feel free to have a look at #1216.