ci/mingw: add second download URL for iconv and freetype

It appears this time GNU broke their ftpmirror, while the primary one is working again.

download.savannah.gnu.org also seems to be having issues.
Never thought I'd see the day where sourceforge is more reliable.

ci/build-mingw64.sh

@@ -5,7 +5,7 @@ mkdir -p "$prefix_dir"
 ln -snf . "$prefix_dir/usr"
 ln -snf . "$prefix_dir/local"
 
-wget="wget -nc --progress=bar:force"
+wget="wget --progress=bar:force"
 gitclone="git clone --depth=1 --recursive --shallow-submodules"
 
 if [[ -z "$TARGET" || -z "$RUST_TARGET" ]]; then
@@ -109,13 +109,15 @@ function gettar {
     [ -z "$dname" ] && dname="${fname%.tar.*}"
     [ -d "$dname" ] && return 0
     local cachename="$(md5sum <<<"$1" | cut -d " " -f 1)"
-    if [[ -n "$DOWNLOAD_CACHE" && -s "$DOWNLOAD_CACHE/$cachename" ]]; then
+    if [ -s "$fname" ]; then
+        : # exists
+    elif [[ -n "$DOWNLOAD_CACHE" && -s "$DOWNLOAD_CACHE/$cachename" ]]; then
         cp -v "$DOWNLOAD_CACHE/$cachename" "$fname"
         cachename=
     else
-        $wget "$1" -O "$fname"
+        $wget "$1" -O "$fname" || return 1
     fi
-    tar -xaf "$fname"
+    tar -xaf "$fname" || return 1
     if [ ! -d "$dname" ]; then
         echo "Error: expected $fname to extract to $dname but it was not created" >&2
         return 2
@@ -146,7 +148,8 @@ function build_if_missing {
 
 _iconv () {
     local ver=1.19
-    gettar "https://ftpmirror.gnu.org/gnu/libiconv/libiconv-${ver}.tar.gz"
+    gettar "https://ftpmirror.gnu.org/gnu/libiconv/libiconv-${ver}.tar.gz" || \
+        gettar "https://ftp.gnu.org/pub/gnu/libiconv/libiconv-${ver}.tar.gz"
     builddir libiconv-${ver}
     ../configure --host=$TARGET $at_flags
     makeplusinstall
@@ -274,7 +277,8 @@ _libplacebo_mark=lib/libplacebo.dll.a
 
 _freetype () {
     local ver=2.14.3
-    gettar "https://download.savannah.gnu.org/releases/freetype/freetype-${ver}.tar.xz"
+    gettar "https://download.savannah.gnu.org/releases/freetype/freetype-${ver}.tar.xz" || \
+        gettar "https://sourceforge.net/projects/freetype/files/freetype-${ver}.tar.xz"
     builddir freetype-${ver}
     meson setup .. --cross-file "$prefix_dir/crossfile"
     makeplusinstall