build: Add cross-compile definitions for Mingw64 on Fedora

Meson uses plain text files for describing the cross-compilation
environment, binaries, and properties.

The values are taken from the mingw wrapper around configure that
Fedora provides for autotools projects.

cross/fedora-mingw64.txt

@@ -0,0 +1,18 @@
+[binaries]
+c = '/usr/bin/x86_64-w64-mingw32-gcc'
+cpp = '/usr/bin/x86_64-w64-mingw32-cpp'
+ar = '/usr/bin/x86_64-w64-mingw32-ar'
+strip = '/usr/bin/x86_64-w64-mingw32-strip'
+pkgconfig = '/usr/bin/x86_64-w64-mingw32-pkg-config'
+exe_wrapper = 'wine'
+
+[properties]
+root = '/usr/x86_64-w64-mingw32/sys-root/mingw'
+c_args = [ '-pipe', '-Wp,-D_FORTIFY_SOURCE=2', '-fexceptions', '--param=ssp-buffer-size=4' ]
+c_link_args = [ '-L/usr/x86_64-w64-mingw32/sys-root/mingw/lib' ]
+
+[host_machine]
+system = 'windows'
+cpu_family = 'x86_64'
+cpu = 'x86_64'
+endian = 'little'