CMakeLists: Don't dump zlib's includes into the top-level directory

CMakeLists.txt

@@ -572,11 +572,9 @@ endif()
 find_package(ZLIB)
 if(ZLIB_FOUND)
   message(STATUS "Using shared zlib")
-  include_directories(${ZLIB_INCLUDE_DIRS})
 else()
   message(STATUS "Shared zlib not found, falling back to the static library")
   add_subdirectory(Externals/zlib)
-  include_directories(Externals/zlib)
 endif()
 
 if(NOT APPLE)

Externals/zlib/CMakeLists.txt

@@ -78,3 +78,8 @@ set(ZLIB_SRCS
 
 add_library(z STATIC ${ZLIB_SRCS} ${ZLIB_DLL_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
 add_library(ZLIB::ZLIB ALIAS z)
+
+target_include_directories(z
+PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}
+)