Building SDL2 from externals is incompatible with Conan's version of
libiconv, a requirement of Conan's Boost package. Solution is to use the
same Boost package in use by the linux-fresh container. This tells CMake
to download boost_1_75_0.tar.xz from yuzu-emu/ext-linux-bin at CMake's
configuration step, much the same way Qt and FFmpeg are downloaded for
Windows.
Also makes DownloadExternals.cmake cross-platform. Although the CMake
code is not entirely specific to Linux, only Linux has Boost libraries
available at ext-linux-bin, whereas there is no equivalent Boost package
for Windows at ext-windows-bin. caveat emptor
The mingw builds aren't submitting telemetry because the curl library
they are linked against is configured to use openSSL and openSSL looks
for the certificates in the users home folder. This keeps it from
contacting web services because it can't communicate over SSL.
This commit adds a download in mingw builds that will download a
precompiled curl for mingw linked against winssl and sspi.
lat9nq