zlib: require minimum Xcode versions for each supported OS, to prevent weird errors when trying to install using a version of Xcode not designed for the current OS version; see https://trac.macports.org/ticket/24599

git-svn-id: https://svn.macports.org/repository/macports/trunk/dports@68569 d073be05-634f-4543-b044-5fe20cf6d1d6

archivers/zlib/Portfile

@@ -1,6 +1,7 @@
 # $Id$
 
 PortSystem              1.0
+PortGroup               xcodeversion 1.0
 
 name                    zlib
 version                 1.2.5
@@ -25,6 +26,8 @@ checksums               md5     be1e89810e66150f5b0327984d8625a0 \
                         sha1    543fa9abff0442edca308772d6cef85557677e02 \
                         rmd160  c6c4c2a2a205061b21487e69234106f5517b4b32
 
+minimum_xcodeversions   {8 2.4.1 9 3.1 10 3.2}
+
 patchfiles              patch-Makefile.in.diff
 
 configure.universal_args