wine build: build win-iconv-mingw-w64-dev, instead of using debian sid

without this, when using a ~week old debian sid snapshot, I got:
```
E: Release file for https://snapshot.debian.org/archive/debian/20220811T031049Z/dists/sid/InRelease is expired (invalid since 1d 11h 56min 39s). Updates for this repository will not be applied.
```

contrib/build-wine/Dockerfile

@@ -24,12 +24,12 @@ RUN dpkg --add-architecture i386 && \
         make \
         mingw-w64 \
         mingw-w64-tools \
-        win-iconv-mingw-w64-dev \
         autotools-dev \
         autoconf \
         autopoint \
         libtool \
         gettext \
+        sudo \
         && \
     rm -rf /var/lib/apt/lists/* && \
     apt-get autoremove -y && \

contrib/build-wine/apt.preferences

@@ -1,7 +1,3 @@
 Package: *
-Pin: release n=bullseye
+Pin: origin "snapshot.debian.org"
-Pin-Priority: 1001
-
-Package: win-iconv-mingw-w64-dev
-Pin: release a=unstable
 Pin-Priority: 1001

contrib/build-wine/apt.sources.list

@@ -1,3 +1,2 @@
 deb https://snapshot.debian.org/archive/debian/20220811T031049Z/ bullseye main non-free contrib
 deb-src https://snapshot.debian.org/archive/debian/20220811T031049Z/ bullseye main non-free contrib
-deb https://snapshot.debian.org/archive/debian/20220811T031049Z/ sid main non-free contrib

contrib/build-wine/make_win.sh

@@ -50,6 +50,28 @@ fi
 if [ -f "$DLL_TARGET_DIR/libzbar-0.dll" ]; then
     info "libzbar already built, skipping"
 else
+    (
+        # As debian bullseye doesn't provide win-iconv-mingw-w64-dev, we need to build it:
+        WIN_ICONV_COMMIT="c9df88a284d448da5434c6ad2737b54a907f888c"
+        # ^ tag "v0.0.8"
+        info "Building win-iconv..."
+        cd "$CACHEDIR"
+        if [ ! -d win-iconv ]; then
+            git clone https://github.com/win-iconv/win-iconv.git
+        fi
+        cd win-iconv
+        if ! $(git cat-file -e ${WIN_ICONV_COMMIT}) ; then
+            info "Could not find requested version $WIN_ICONV_COMMIT in local clone; fetching..."
+            git fetch --all
+        fi
+        git reset --hard
+        git clean -dfxq
+        git checkout "${WIN_ICONV_COMMIT}^{commit}"
+
+        CC="${GCC_TRIPLET_HOST}-gcc" make -j4 || fail "Could not build win-iconv"
+        # FIXME avoid using sudo
+        sudo make install prefix="/usr/${GCC_TRIPLET_HOST}"  || fail "Could not install win-iconv"
+    )
     "$CONTRIB"/make_zbar.sh || fail "Could not build zbar"
 fi
 

contrib/freeze_containers_distro.sh

@@ -38,8 +38,6 @@ echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_APPIMAGE_DISTRO} main non-free contrib
 # build-wine
 echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main non-free contrib" >$contrib/build-wine/apt.sources.list
 echo "deb-src ${DEBIAN_SNAPSHOT} ${DEBIAN_WINE_DISTRO} main non-free contrib" >>$contrib/build-wine/apt.sources.list
-# we need win-iconv-mingw-w64-dev which is only in sid/unstable
-echo "deb ${DEBIAN_SNAPSHOT} unstable main non-free contrib" >>$contrib/build-wine/apt.sources.list
 
 # android
 echo "deb ${DEBIAN_SNAPSHOT} ${DEBIAN_ANDROID_DISTRO} main non-free contrib" >$contrib/android/apt.sources.list