[embedded] Mark embedded Concurrency as IS_FRAGILE (no library evolution)

Author: kubamracek

stdlib/public/Concurrency/CMakeLists.txt

@@ -207,7 +207,7 @@ if(SWIFT_SHOULD_BUILD_EMBEDDED_STDLIB AND SWIFT_SHOULD_BUILD_EMBEDDED_CONCURRENC
       embedded-concurrency-${mod}
       swift_Concurrency
       STATIC
-      IS_STDLIB
+      IS_STDLIB IS_FRAGILE
 
       ${SWIFT_RUNTIME_CONCURRENCY_C_SOURCES}
       # TODO: Only a handful of Swift Concurrency .swift sources, for now.