cmake: Ensure that CMAKE_CODESIGN is set instead of trying to run empty

commands.

Author: Doug Coleman

benchmark/cmake/modules/AddSwiftBenchmarkSuite.cmake

@@ -321,6 +321,7 @@ function (swift_benchmark_compile_archopts)
         "-c"
         "-o" "${objcfile}")
 
+  precondition(CMAKE_CODESIGN MESSAGE "CMAKE_CODESIGN is required, please set it")
   add_custom_command(
       OUTPUT "${OUTPUT_EXEC}"
       DEPENDS

cmake/modules/AddSwift.cmake

@@ -465,6 +465,7 @@ function(_add_swift_lipo_target)
   is_darwin_based_sdk("${LIPO_SDK}" IS_DARWIN)
   if(IS_DARWIN)
     if(LIPO_CODESIGN)
+      precondition(CMAKE_CODESIGN MESSAGE "CMAKE_CODESIGN is required, please set it")
       set(codesign_command COMMAND "${CMAKE_CODESIGN}" "-f" "-s" "-" "${LIPO_OUTPUT}")
     endif()
     # Use lipo to create the final binary.