Upgrade libpng and correct release-monitoring ID

Ensure only stable verions are considered 'latest'
Better multi-OS support for printf instead of echo

build.sh

@@ -30,7 +30,7 @@ if ! type docker >/dev/null; then
 fi
 
 # Update base images
-for baseimage in debian:wheezy debian:stretch alpine:edge; do
+for baseimage in debian:jessie debian:stretch alpine:edge; do
   docker pull $baseimage
 done
 

build/lin.sh

@@ -24,7 +24,7 @@ VERSION_GSF=1.14.46
 VERSION_EXIF=0.6.21
 VERSION_LCMS2=2.9
 VERSION_JPEG=2.0.2
-VERSION_PNG16=1.6.34
+VERSION_PNG16=1.6.37
 VERSION_WEBP=1.0.2
 VERSION_TIFF=4.0.10
 VERSION_ORC=0.4.28
@@ -54,7 +54,7 @@ without_patch() {
 # Check for newer versions
 ALL_AT_VERSION_LATEST=true
 version_latest() {
-  VERSION_LATEST=$(curl -s https://release-monitoring.org/api/project/$3 | jq -r '.version' | tr -d v)
+  VERSION_LATEST=$(curl -s https://release-monitoring.org/api/project/$3 | jq -r '.versions[]' | grep -E -m1 '^[0-9]+(.[0-9]+)*$')
   if [ "$VERSION_LATEST" != "$2" ]; then
     ALL_AT_VERSION_LATEST=false
     echo "$1 version $2 has been superseded by $VERSION_LATEST"
@@ -68,15 +68,15 @@ version_latest "gsf" "$VERSION_GSF" "1980"
 version_latest "exif" "$VERSION_EXIF" "1607"
 version_latest "lcms2" "$VERSION_LCMS2" "9815"
 version_latest "jpeg" "$VERSION_JPEG" "1648"
-version_latest "png" "$VERSION_PNG16" "15294"
+version_latest "png" "$VERSION_PNG16" "1705"
 version_latest "webp" "$VERSION_WEBP" "1761"
 version_latest "tiff" "$VERSION_TIFF" "13521"
 version_latest "orc" "$VERSION_ORC" "2573"
 version_latest "gettext" "$VERSION_GETTEXT" "898"
 #version_latest "gdkpixbuf" "$VERSION_GDKPIXBUF" "9533" # latest version requires meson instead of autotools
 version_latest "freetype" "$VERSION_FREETYPE" "854"
 version_latest "expat" "$VERSION_EXPAT" "770"
-#version_latest "uuid" "$VERSION_UUID" "8179" # latest version in release monitoring is release candidate
+version_latest "uuid" "$VERSION_UUID" "8179"
 version_latest "fontconfig" "$VERSION_FONTCONFIG" "827"
 version_latest "harfbuzz" "$VERSION_HARFBUZZ" "1299"
 version_latest "pixman" "$VERSION_PIXMAN" "3648"
@@ -303,7 +303,7 @@ rm -rf pkgconfig .libs *.la libvipsCC*
 
 # Create JSON file of version numbers
 cd ${TARGET}
-echo "{\n\
+printf "{\n\
   \"cairo\": \"${VERSION_CAIRO}\",\n\
   \"croco\": \"${VERSION_CROCO}\",\n\
   \"exif\": \"${VERSION_EXIF}\",\n\
@@ -333,7 +333,7 @@ echo "{\n\
   \"zlib\": \"${VERSION_ZLIB}\"\n\
 }" >versions.json
 
-echo "\"${PLATFORM}\"" >platform.json
+printf "\"${PLATFORM}\"" >platform.json
 
 # Create .tar.gz
 tar czf /packaging/libvips-${VERSION_VIPS}-${PLATFORM}.tar.gz include lib *.json