Add zlib recipe.toml

recipes/zlib/recipe.toml

+[source]
+tar = "http://zlib.net/zlib-1.2.11.tar.gz"
+
+[build]
+template = "custom"
+script = """
+    export LDFLAGS="--static"
+    # See https://stackoverflow.com/questions/21396988/zlib-build-not-configuring-properly-with-cross-compiler-ignores-ar.
+    CHOST="${TARGET}" "${COOKBOOK_SOURCE}/configure" \
+        --prefix="" \
+        --static
+    make -j "$(nproc)"
+    make install DESTDIR="${COOKBOOK_STAGE}"
+"""