Set CMake Policy CMP0063 to NEW within KWSys

Make KWSys honor visibility properties set by the consuming project.

Change-Id: I66b982d955089bc78f88e29c4a7bc19bf2abec00

CMakeLists.txt

@@ -70,6 +70,7 @@ CMAKE_MINIMUM_REQUIRED(VERSION 2.6.3 FATAL_ERROR)
 FOREACH(p
     CMP0025 # CMake 3.0, Compiler id for Apple Clang is now AppleClang.
     CMP0056 # CMake 3.2, Honor link flags in try_compile() source-file signature.
+    CMP0063 # CMake 3.3, Honor visibility properties for all target types.
     )
   IF(POLICY ${p})
     CMAKE_POLICY(SET ${p} NEW)