Building kcov failed on Windows

[Fullstop000]

https://travis-ci.org/Fullstop000/wickdb/jobs/602617170

Done. Your build exited with 0.
CMake Error at C:/Program Files/CMake/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find ZLIB (missing: ZLIB_LIBRARY ZLIB_INCLUDE_DIR)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  C:/Program Files/CMake/share/cmake-3.15/Modules/FindZLIB.cmake:115 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  src/CMakeLists.txt:8 (find_package)
/c/Users/travis/.travis/functions: line 109: make: command not found
/c/Users/travis/.travis/functions: line 109: make: command not found
/c/Users/travis/.travis/functions: line 109: ./kcov-build/usr/local/bin/kcov: No such file or directory
bash: /dev/fd/63: No such file or directory