Merge pull request #80883 from edymtt/emiotto/mark-executorimpl_cpp-optional-6.2

[6.2] CMake Embedded Stdlib: mark `ExecutorImpl.cpp` as optional

Author: edymtt

stdlib/public/Concurrency/CMakeLists.txt

@@ -259,6 +259,7 @@ if(SWIFT_SHOULD_BUILD_EMBEDDED_STDLIB AND SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENC
   set(SWIFT_STDLIB_CONCURRENCY_TRACING FALSE)
   set(SWIFT_STDLIB_HAS_ENVIRON FALSE)
   set(SWIFT_STDLIB_HAS_ASL FALSE)
+  list(APPEND LLVM_OPTIONAL_SOURCES ExecutorImpl.cpp)
 
   foreach(entry ${EMBEDDED_STDLIB_TARGET_TRIPLES})
     string(REGEX REPLACE "[ \t]+" ";" list "${entry}")