[embedded] Don't build embedded Concurrency without SwiftCompilerSources

Author: kubamracek

stdlib/public/Concurrency/CMakeLists.txt

@@ -179,6 +179,8 @@ set(SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENCY TRUE)
 is_build_type_optimized("${SWIFT_STDLIB_BUILD_TYPE}" swift_optimized)
 if(NOT swift_optimized)
   set(SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENCY FALSE)
+elseif(BOOTSTRAPPING_MODE STREQUAL "OFF")
+  set(SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENCY FALSE)
 endif()
 if(SWIFT_SHOULD_BUILD_EMBEDDED_STDLIB AND SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENCY)
   add_custom_target(embedded-concurrency ALL)