Silence CMake policy warning on macos.

See: https://cmake.org/cmake/help/v3.0/policy/CMP0042.html

CMakeLists.txt

@@ -174,6 +174,9 @@ include_directories(src contrib/epee/include external "${CMAKE_BINARY_DIR}/versi
 
 if(APPLE)
   include_directories(SYSTEM /usr/include/malloc)
+  if(POLICY CMP0042)
+    cmake_policy(SET CMP0042 NEW)
+  endif()
 endif()
 
 if(MSVC OR MINGW)

contrib/otshell_utils/CMakeLists.txt

@@ -3,6 +3,10 @@ project (otshell CXX)
 
 # Add executable
 
+if(APPLE AND POLICY CMP0042)
+	cmake_policy(SET CMP0042 NEW)
+endif()
+
 file(GLOB otshell_utils_sources # All files in directory:
 	"*.h"
 	"*.hpp"