Update zlib CMakeLists

extern/zlib/CMakeLists.txt

@@ -1,48 +1,42 @@
 if (APPLE)
-# use toolchain zlib
-find_package(ZLIB REQUIRED)
-add_library(z ALIAS ZLIB::ZLIB) # alias hack to allow use from global context
-set(ZLIB_LIBRARIES z CACHE STRING "zlib libraries" FORCE)
-else()
-if(NOT WIN32 AND NOT NX) # remove WIN32 when specter/freetype is gone
-find_library(ZLIB_LIB NAMES zlib z)
-endif()
-if(NOT ZLIB_LIB)
-message(STATUS "Using Athena's built-in zlib")
-add_library(z
-    adler32.c
-    compress.c
-    crc32.c
-    deflate.c
-    infback.c
-    inffast.c
-    inflate.c
-    inftrees.c
-    trees.c
-    uncompr.c
-    zutil.c
-    crc32.h
-    deflate.h
-    gzguts.h
-    inffast.h
-    inffixed.h
-    inflate.h
-    inftrees.h
-    trees.h
-    zconf.h
-    zlib.h
-    zutil.h)
-if(WIN32 AND NOT UNIX)
-install(FILES zconf.h zlib.h DESTINATION include COMPONENT zlib)
-install(TARGETS z DESTINATION lib COMPONENT zlib)
-else()
-target_compile_options(z PRIVATE -Wno-implicit-fallthrough)
-endif()
-set(ZLIB_LIBRARIES z CACHE STRING "zlib libraries" FORCE)
-set(ZLIB_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE PATH "zlib include directory" FORCE)
-else()
-set(ZLIB_LIBRARIES ${ZLIB_LIB} CACHE PATH "zlib libraries" FORCE)
-find_path(ZLIB_INCLUDE_DIR zlib.h PATHS "${PNG_LIB}/../../include")
-message(STATUS "Using zlib at ${ZLIB_LIB}, include: ${ZLIB_INCLUDE_DIR}")
-endif()
-endif()
+  # always use toolchain zlib
+  set(ZLIB_REQUIRED REQUIRED)
+endif ()
+find_package(ZLIB ${ZLIB_REQUIRED})
+if (ZLIB_FOUND)
+  add_library(z ALIAS ZLIB::ZLIB) # alias hack to allow use from global context
+  set(ZLIB_LIBRARIES z CACHE STRING "zlib libraries" FORCE)
+else ()
+  message(STATUS "Using Athena's built-in zlib")
+  add_library(z
+      adler32.c
+      compress.c
+      crc32.c
+      deflate.c
+      infback.c
+      inffast.c
+      inflate.c
+      inftrees.c
+      trees.c
+      uncompr.c
+      zutil.c
+      crc32.h
+      deflate.h
+      gzguts.h
+      inffast.h
+      inffixed.h
+      inflate.h
+      inftrees.h
+      trees.h
+      zconf.h
+      zlib.h
+      zutil.h)
+  if (WIN32 AND NOT UNIX)
+    install(FILES zconf.h zlib.h DESTINATION include COMPONENT zlib)
+    install(TARGETS z DESTINATION lib COMPONENT zlib)
+  else ()
+    target_compile_options(z PRIVATE -Wno-implicit-fallthrough)
+  endif ()
+  set(ZLIB_LIBRARIES z CACHE STRING "zlib libraries" FORCE)
+  set(ZLIB_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR} CACHE PATH "zlib include directory" FORCE)
+endif ()