Wrap cmake policies in an if statement

Author: TrentHouliston

Diff for: cmake/FindArduinoCtags.cmake

@@ -6,7 +6,9 @@ function(get_ctags)
 
   # Prevent warnings in CMake>=3.24 regarding ExternalProject_Add()
   # cf. https://cmake.org/cmake/help/latest/policy/CMP0135.html
-  cmake_policy(SET CMP0135 OLD)
+  if (POLICY CMP0135)
+    cmake_policy(SET CMP0135 OLD)
+  endif()
 
   cmake_host_system_information(
     RESULT HOSTINFO

Diff for: cmake/ensure_core_deps.cmake

@@ -61,7 +61,9 @@ function(declare_deps CORE_VERSION)
 
   # Prevent warnings in CMake>=3.24 regarding ExternalProject_Add()
   # cf. https://cmake.org/cmake/help/latest/policy/CMP0135.html
-  cmake_policy(SET CMP0135 OLD)
+  if (POLICY CMP0135)
+    cmake_policy(SET CMP0135 OLD)
+  endif()
 
   file(REAL_PATH "${DL_DIR}/package_stmicroelectronics_index.json" JSONFILE)
   if (NOT EXISTS ${JSONFILE})