cmake: Set CMP0056 to NEW

When Android is compiled with "-static" in CMAKE_EXE_LINKER_FLAGS, only the
shared version of libc has utimensat.  By setting CMP0056 to NEW,
CMAKE_EXE_LINKER_FLAGS is passed to the try_compile in KWSYS_PLATFORM_CXX_TEST
so KWSYS_CXX_HAS_UTIMENSAT gets the correct result.

Change-Id: Ia5ff7abaafb92e043927b57c5f2858259195235f

CMakeLists.txt

@@ -88,6 +88,9 @@ CMAKE_MINIMUM_REQUIRED(VERSION 2.6.3 FATAL_ERROR)
 IF(POLICY CMP0025)
   CMAKE_POLICY(SET CMP0025 NEW)
 ENDIF()
+IF(POLICY CMP0056)
+  CMAKE_POLICY(SET CMP0056 NEW)
+ENDIF()
 
 #-----------------------------------------------------------------------------
 # If a namespace is not specified, use "kwsys" and enable testing.