Migrate more scripts to git

scripts.d/20-zlib.sh

@@ -1,20 +1,16 @@
 #!/bin/bash
 
-ZLIB_SRC="https://zlib.net/zlib-1.2.12.tar.gz"
+SCRIPT_REPO="https://github.com/madler/zlib.git"
+SCRIPT_COMMIT="21767c654d31d2dccdde4330529775c6c5fd5389"
 
 ffbuild_enabled() {
     return 0
 }
 
 ffbuild_dockerbuild() {
-    mkdir zlib
+    git-mini-clone "$SCRIPT_REPO" "$SCRIPT_COMMIT" zlib
     cd zlib
 
-    wget "$ZLIB_SRC" -O zlib.tar.gz
-    tar xaf zlib.tar.gz
-    rm zlib.tar.gz
-    cd zlib*
-
     local myconf=(
         --prefix="$FFBUILD_PREFIX"
         --static