use global setup script

ios/setup_libpng.sh

@@ -1,18 +0,0 @@
-#!/bin/sh
-
-if [ ! -d 'mapnik-packaging' ]; then
-  git clone --depth=0 https://github.com/mapnik/mapnik-packaging.git
-fi
-cd mapnik-packaging/osx/
-git pull
-export CXX11=true
-(source iPhoneSimulator.sh; ./scripts/build_png.sh; \
- source MacOSX.sh;          ./scripts/build_png.sh; \
- source iPhoneOS.sh;        ./scripts/build_png.sh; \
- source iPhoneOSs.sh;       ./scripts/build_png.sh; \
- source iPhoneOS64.sh;      ./scripts/build_png.sh; \
- ./scripts/make_universal.sh)
-export UNIVERSAL_LIBS=`pwd`/out/build-cpp11-libcpp-universal/
-export PNG_INCLUDES=`pwd`/out/build-cpp11-libcpp-i386/include
-cd ../../
-./configure --png-libpath=${UNIVERSAL_LIBS} --png-includes=${PNG_INCLUDES}

setup-libraries.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+set -e -u
+
+if [ ! -d 'mapnik-packaging' ]; then
+  git clone --depth=0 https://github.com/mapnik/mapnik-packaging.git
+fi
+
+cd mapnik-packaging/osx/
+git pull
+
+export CXX11=true
+
+source iPhoneOS.sh
+    if [ ! -f out/build-cpp11-libcpp-armv7/lib/libpng.a ] ; then ./scripts/build_png.sh ; fi
+    echo '     ...done'
+
+source iPhoneOSs.sh
+    if [ ! -f out/build-cpp11-libcpp-armv7s/lib/libpng.a ] ; then ./scripts/build_png.sh ; fi
+    echo '     ...done'
+
+source iPhoneOS64.sh
+    if [ ! -f out/build-cpp11-libcpp-arm64/lib/libpng.a ] ; then ./scripts/build_png.sh ; fi
+    echo '     ...done'
+
+source iPhoneSimulator.sh
+    if [ ! -f out/build-cpp11-libcpp-i386/lib/libpng.a ] ; then ./scripts/build_png.sh ; fi
+    echo '     ...done'
+
+source MacOSX.sh
+    if [ ! -f out/build-cpp11-libcpp-x86_64/lib/libpng.a ] ; then ./scripts/build_png.sh ; fi
+    if [ ! -f out/build-cpp11-libcpp-x86_64/lib/libglfw3.a ] ; then ./scripts/build_glfw.sh ; fi
+    if [ ! -f out/build-cpp11-libcpp-x86_64/lib/libssl.a ] ; then ./scripts/build_openssl.sh ; fi
+    if [ ! -f out/build-cpp11-libcpp-x86_64/lib/libcurl.a ] ; then ./scripts/build_curl.sh ; fi
+    echo '     ...done'
+
+./scripts/make_universal.sh
+
+cd ../../
+./configure --pkg-config-root=`pwd`/mapnik-packaging/osx/out/build-cpp11-libcpp-universal/lib/pkgconfig