cross-zlib: fix url/license

and improve the meta package description

mingw-w64-cross-zlib/PKGBUILD

@@ -6,10 +6,11 @@ pkgbase="${_mingw_suff}-zlib"
 pkgname=("${_mingw_suff}-zlib" "${_mingw_suff}-ucrt64-zlib" "${_mingw_suff}-mingw32-zlib" "${_mingw_suff}-mingw64-zlib")
 pkgdesc="Compression library implementing the deflate compression method found in gzip and PKZIP"
 pkgver=1.3.1
-pkgrel=2
+pkgrel=3
 arch=('i686' 'x86_64')
-url="https://mingw-w64.sourceforge.io/"
-license=('custom')
+url="https://www.zlib.net/"
+msys2_repository_url="https://github.com/madler/zlib"
+license=('spdx:Zlib')
 groups=("${_mingw_suff}-toolchain" "${_mingw_suff}")
 depends=()
 makedepends=("${_mingw_suff}-gcc" 'autotools')
@@ -62,6 +63,7 @@ build() {
 }
 
 package_mingw-w64-cross-zlib() {
+  pkgdesc+=" (meta package, for backward compatibility)"
   depends=(
     "${_mingw_suff}-ucrt64-zlib"
     "${_mingw_suff}-mingw32-zlib"