Install a getopt library on Windows.

Yes, getopt is posix and is not present by default on Windows.
https://github.com/takamin/win-c seems a pretty functional getopt_long
implementation.

appveyor.yml

@@ -52,6 +52,7 @@ build_script:
   - IF "%USE_CACHE%" NEQ "1" appveyor\install_aria2.cmd
   - IF "%USE_CACHE%" NEQ "1" appveyor\install_mustache.cmd
   - IF "%USE_CACHE%" NEQ "1" appveyor\install_libmicrohttpd.cmd
+  - IF "%USE_CACHE%" NEQ "1" appveyor\install_getopt.cmd
   - IF "%USE_CACHE%" NEQ "1" %MINGW64_RUN% "cd /c/projects/kiwix-build && appveyor/create_cache.sh"
   - appveyor\install_libzim.cmd
   - appveyor\install_kiwix-lib.cmd

appveyor/install_getopt.cmd

@@ -0,0 +1,15 @@
+REM ========================================================
+REM Install getopt
+curl -fsSL -O https://github.com/takamin/win-c/archive/v1.0.zip || exit /b 1
+7z x v1.0.zip -o. || exit /b 1
+cd win-c-1.0
+mkdir build
+cd build
+cmake -G"NMake Makefiles" -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=%EXTRA_DIR% .. || exit /b 1
+dir
+nmake install || exit /b 1
+copy ..\include\getopt.h %EXTRA_DIR%\include
+cd ..\..
+
+dir %EXTRA_DIR%\include
+dir %EXTRA_DIR%\lib

appveyor/install_kiwix-tools.cmd

@@ -3,7 +3,7 @@ REM Install kiwix-lib
 git clone https://github.com/kiwix/kiwix-tools.git || exit /b 1
 cd kiwix-tools
 set "CPPFLAGS=-I%EXTRA_DIR%/include"
-set "LDFLAGS=-lshlwapi -lwinmm"
+set "LDFLAGS=-lshlwapi -lwinmm -llibwinc"
 meson . build --prefix %EXTRA_DIR% -Dstatic-linkage=true --buildtype release || exit /b 1
 cd build
 ninja || exit /b 1