[gl2ps] do not depend on PNG or ZLIB

since only EPS backend is used by ROOT graf3d plotter

Author: ferdymercury

builtins/gl2ps/CMakeLists.txt

@@ -33,6 +33,8 @@ ExternalProject_Add(
              -DCMAKE_POSITION_INDEPENDENT_CODE=ON
              -DCMAKE_C_VISIBILITY_PRESET=hidden
              -DCMAKE_POLICY_VERSION_MINIMUM=3.5
+             -DENABLE_PNG=OFF
+             -DENABLE_ZLIB=OFF
   BUILD_COMMAND ${CMAKE_COMMAND} --build . ${ROOT_GL2PS_BUILD_COMMAND_FLAGS}
   INSTALL_COMMAND ${CMAKE_COMMAND} --build . ${ROOT_GL2PS_BUILD_COMMAND_FLAGS} --target install
   LOG_CONFIGURE 1