zlib-1.2.11: Add a patch to cross-compile for macos

packages/zlib/1.2.11/0003-crossbuild-macos-libtool.patch

@@ -0,0 +1,34 @@
+commit 1f6bc557ec5c90eced96ae81ff1d443ee5770993
+Author: Heiko Lewin <heiko.lewin@worldiety.de>
+Date:   Fri May 22 03:32:33 2020 +0200
+
+    configure: use LIBTOOL variable for Darwin builds
+
+diff --git a/configure b/configure
+index e974d1f..0c88bf9 100755
+--- a/configure
++++ b/configure
+@@ -66,6 +66,12 @@ if "${CROSS_PREFIX}nm" --version >/dev/null 2>/dev/null || test $? -lt 126; then
+ else
+     NM=${NM-"nm"}
+ fi
++if "${CROSS_PREFIX}libtool" --version >/dev/null 2>/dev/null || test $? -lt 126; then
++    LIBTOOL=${LIBTOOL-"${CROSS_PREFIX}libtool"}
++    test -n "${CROSS_PREFIX}" && echo Using ${LIBTOOL} | tee -a configure.log
++else
++    LIBTOOL=${LIBTOOL-"libtool"}
++fi
+ 
+ # set defaults before processing command line options
+ LDCONFIG=${LDCONFIG-"ldconfig"}
+@@ -241,8 +247,8 @@ if test "$gcc" -eq 1 && ($cc -c $test.c) >> configure.log 2>&1; then
+              SHAREDLIBV=libz.$VER$shared_ext
+              SHAREDLIBM=libz.$VER1$shared_ext
+              LDSHARED=${LDSHARED-"$cc -dynamiclib -install_name $libdir/$SHAREDLIBM -compatibility_version $VER1 -current_version $VER3"}
+-             if libtool -V 2>&1 | grep Apple > /dev/null; then
+-                 AR="libtool"
++             if ${LIBTOOL} -V 2>&1 | grep Apple > /dev/null; then
++                 AR="${LIBTOOL}"
+              else
+                  AR="/usr/bin/libtool"
+              fi