[WIP] Bundle lgamma from fdlibm for MSVC

Under MSVC, `expected_mutual_info_fast` fails to compile because `lgamma` is not part of that distribution of `math.h`.  Here is my attempt at bundling it. 

At the moment, it doesn't work: it still doesn't find the symbol under Windows.  Under my normal (MacOS X) environment it builds, but I don't know how to check whether it properly takes `lgamma` from the bundle or from the system `math.h`.  Still working on it, but putting this here in case anyone can spot what I'm doing wrong and give me a little push.