From 22d174231190d935e7c31b8e6ac84d49c81a861f Mon Sep 17 00:00:00 2001
From: wraitii <wraitii@wildfiregames.com>
Date: Thu, 26 Nov 2020 09:15:36 +0000
Subject: [PATCH] Fix MacOS libpng compilation against the 10.12 SDK

This was SVN commit r24260.
---
 libraries/osx/build-osx-libs.sh | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/libraries/osx/build-osx-libs.sh b/libraries/osx/build-osx-libs.sh
index b1fbf8f3a2..9532ab20b7 100755
--- a/libraries/osx/build-osx-libs.sh
+++ b/libraries/osx/build-osx-libs.sh
@@ -471,8 +471,9 @@ then
   tar -xf $LIB_ARCHIVE
   pushd $LIB_DIRECTORY
 
-  (./configure CFLAGS="$CFLAGS" \
-      LDFLAGS="$LDFLAGS" \
+  # libpng has no flags for zlib but the 10.12 version is too old, so link our own.
+  (./configure CFLAGS="$CFLAGS" CPPFLAGS=" -I $ZLIB_DIR/include "\
+      LDFLAGS="$LDFLAGS -L$ZLIB_DIR/lib" \
       --prefix=$INSTALL_DIR \
       --enable-shared=no \
     && make ${JOBS} && make install) || die "libpng build failed"