I'm just reporting. I faced an issue while tried to build libpng on Amazon Linux (Red Hat based). But I got following error:
libtool: link: gcc -g -O2 -o .libs/pngfix contrib/tools/pngfix.o ./.libs/libpng16.so -lz -lm ./.libs/libpng16.so: undefined reference to `inflateValidate' collect2: error: ld returned 1 exit status
I checked environment variables and they were set normally.
nm tool displayed that
inflateValidate was in zlib library exports. I hope my solution (see below) will help somebody and will save his time.