add fcgi2 to microsoft/vcpkg

[longhuan2018]

Using Microsoft's vcpkg, you can easily compile code under windows, linux, osx, just use vcpkg install fastcgi: x64-windows
In order to make it compile, I modified the libfcgi.mak file to support compilation under x64 and uwp, and modified acinclude.m4 so that it does not report an error under linux.
I have submitted a PR 7824 to microsoft/vcpkg,
Code changes, I also submitted a PR #40 to the code base, please see if it is worth merging