PR #4996 is incomplete! It is missing that PNG depends on ZLIB.

Fix for dependencies/png/CMakeLists.txt: Insert the following after line

target_link_libraries(_BUNDLED_PNG PUBLIC "$<BUILD_LOCAL_INTERFACE:ZLIB::ZLIB>")

This means that HPDF must also depend on ZLIB, otherwise it will not work with object or static libraries.

Fix for dependencies/hpdf/CMakeLists.txt: Replace line

	target_link_libraries(_BUNDLED_HPDF PUBLIC "$<BUILD_LOCAL_INTERFACE:PNG::PNG>" "$<BUILD_LOCAL_INTERFACE:ZLIB::ZLIB>")

Fix for PDF/CMakeLists.txt: Replace line

target_link_libraries(PDF PRIVATE "$<BUILD_LOCAL_INTERFACE:PNG::PNG>" "$<BUILD_LOCAL_INTERFACE:ZLIB::ZLIB>")