Use CMake's built-in zlib finder
Second try. Closes #424 (closed)
Appveyor build: https://ci.appveyor.com/project/certik/lfortran-ts83e/builds/39945377
Second try. Closes #424 (closed)
Appveyor build: https://ci.appveyor.com/project/certik/lfortran-ts83e/builds/39945377