Stop installing MSYS2 packages.
We're compiling for mingw, so we only need mingw packages.
Run pacman in verbose mode.
Explicitly install pkg-config and xz, to future-proof our builds.
Diagnostics for 28399.
Closes ticket 27765
This commit also changes the appveyor file to a unified line ending
style, since the old one was pretty confused. Use "-b" to see the
real differences.
As of August 29, 2018, Appveyor images come with gcc 8.2.0 by
default. 64-bit Windows executables compiled with gcc 8.2.0 and
tor's --enable-gcc-hardening crash.
Fixes bug 27460; bugfix on 0.3.4.1-alpha.
