CMake: set CMP0026 to OLD

Setting this to OLD allows us to read the LOCATION property out of
targets. This is deprecated but still nicer for what we need to with
our resource copying. We should revisit this later.

CMakeLists.txt

@@ -37,6 +37,7 @@ endmacro()
 set_policy(CMP0020 NEW)
 set_policy(CMP0017 NEW)
 set_policy(CMP0058 NEW)
+set_policy(CMP0026 OLD)
 
 include(utils)
 include(CompilerFlags)