Rename zconf.h in CMakeLists.txt to move it out of the way.

CMakeLists.txt

@@ -67,11 +67,11 @@ if(NOT CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_CURRENT_BINARY_DIR)
     # If we're doing an out of source build and the user has a zconf.h
     # in their source tree...
     if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h)
-        message(FATAL_ERROR
-            "You must remove ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h "
-            "from the source tree.  This file is included with zlib "
-            "but CMake generates this file for you automatically "
-            "in the build directory.")
+        message(STATUS "Renaming")
+        message(STATUS "    ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h")
+        message(STATUS "to 'zconf.h.included' because this file is included with zlib")
+        message(STATUS "but CMake generates it automatically in the build directory.")
+        file(RENAME ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h ${CMAKE_CURRENT_SOURCE_DIR}/zconf.h.included)
   endif()
 endif()