cmake: fix ZLIB_INCLUDE_DIRS use

CMake 2.8's FindZLIB.cmake documents ZLIB_INCLUDE_DIRS, see
http://www.cmake.org/cmake/help/v2.8.0/cmake.html#module:FindZLIB

Bug: https://github.com/bagder/curl/pull/123

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cbf6c0e4cffd5fae31a9f426daf585c98c3dc0d8..45f46ec5e1a51aa6e0ba6f668073a68c65e10df6 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -411,7 +411,7 @@ if(CURL_ZLIB)
     set(HAVE_ZLIB ON)
     set(HAVE_LIBZ ON)
     list(APPEND CURL_LIBS ${ZLIB_LIBRARIES})
-    include_directories(${ZLIB_INCLUDE_DIR})
+    include_directories(${ZLIB_INCLUDE_DIRS})
   endif()
 endif()