Add a simple MSVC cross-compile script for testing

This is not generally useful, but with a suitable setup allows for smoke
testing of an MSVC build without needing Windows.

Toolchain-msvc.cmake

@@ -0,0 +1,18 @@
+set(CMAKE_SYSTEM_NAME Windows)
+set(CMAKE_SYSTEM_PROCESSOR X86_64)
+
+set(CMAKE_BUILD_TYPE "Release")
+set(CMAKE_C_COMPILER "x86_64-pc-windows-msvc-gcc")
+set(CMAKE_CXX_COMPILER "x86_64-pc-windows-msvc-g++")
+set(CMAKE_EXE_LINKER_FLAGS "/winsdkdir:/usr/x86_64-pc-windows-msvc/winsdk/sdk /vctoolsdir:/usr/x86_64-pc-windows-msvc/winsdk/crt /libpath:/usr/x86_64-pc-windows-msvc/winsdk/sdk/lib/um/x64")
+set(CMAKE_SHARED_LINKER_FLAGS ${CMAKE_EXE_LINKER_FLAGS})
+set(CMAKE_MT "llvm-mt")
+
+set(CMAKE_FIND_ROOT_PATH /usr/x86_64-pc-windows-msvc)
+
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+
+set(ENV{PKG_CONFIG_DIR} "")
+set(ENV{PKG_CONFIG_LIBDIR} "/usr/x86_64-pc-windows-msvc/lib/pkgconfig")

msvc.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+set -ex
+
+qt="$HOME/Qt/6.6.0/msvc2019_64"
+
+nproc=$(getconf _NPROCESSORS_ONLN)
+
+[[ -e build/dist ]] && exit 1
+
+(
+mkdir build-msvc
+cd build-msvc
+cmake .. -DWITH_QT6=ON -DCMAKE_PREFIX_PATH="${qt}" -DCMAKE_BUILD_TYPE=Release -DCMAKE_TOOLCHAIN_FILE=Toolchain-msvc.cmake -DSOUND=QT -DWITH_BUNDLED_FMT=ON -DDIST_INSTALL=ON
+make -j${nproc}
+make install
+)
+
+for dll in libpng16.dll sndfile.dll turbojpeg.dll zlib1.dll
+do
+    cp "/usr/x86_64-pc-windows-msvc/bin/${dll}" build/dist
+done
+
+for dll in Qt6Core.dll Qt6Gui.dll Qt6Multimedia.dll Qt6Network.dll Qt6Widgets.dll
+do
+    cp "${qt}/bin/${dll}" build/dist
+done
+
+mkdir -p "build/dist/plugins/platforms"
+cp "${qt}/plugins/platforms/qwindows.dll" "build/dist/plugins/platforms"
+mkdir -p "build/dist/plugins/multimedia"
+cp "${qt}/plugins/multimedia/windowsmediaplugin.dll" "build/dist/plugins/multimedia"
+
+cp licenses/*.txt build/dist
+cp fonts/Gargoyle*.ttf build/dist
+cp fonts/unifont*.otf build/dist
+mkdir build/dist/themes
+cp themes/*.json build/dist/themes
+unix2dos -n garglk/garglk.ini build/dist/garglk.ini