[cxx-interop] Make Cxx and CxxStdlib libraries resilient

This enables library evolution for the two libraries that form the Swift overlay for the C++ standard library.

rdar://129169673

Author: egorzhdan

stdlib/public/Cxx/CMakeLists.txt

@@ -6,7 +6,7 @@ if(SWIFT_STDLIB_SUPPORT_BACK_DEPLOYMENT)
   list(APPEND SWIFT_CXX_DEPS copy-legacy-layouts)
 endif()
 
-add_swift_target_library(swiftCxx STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY IS_FRAGILE
+add_swift_target_library(swiftCxx STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY
     CxxConvertibleToBool.swift
     CxxConvertibleToCollection.swift
     CxxDictionary.swift

stdlib/public/Cxx/std/CMakeLists.txt

@@ -33,7 +33,7 @@ endif()
 #
 # The overlay is fragile (i.e. it does not use library evolution)
 # as it's not ABI stable.
-add_swift_target_library(swiftCxxStdlib STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY IS_FRAGILE
+add_swift_target_library(swiftCxxStdlib STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_ONLY
     std.swift
     Chrono.swift
     String.swift
@@ -50,6 +50,7 @@ add_swift_target_library(swiftCxxStdlib STATIC NO_LINK_NAME IS_STDLIB IS_SWIFT_O
     SWIFT_COMPILE_FLAGS ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS} ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
     -cxx-interoperability-mode=default
     -Xfrontend -module-interface-preserve-types-as-written
+    -enable-experimental-feature AssumeResilientCxxTypes
 
     SWIFT_COMPILE_FLAGS_LINUX
     ${SWIFT_SDK_LINUX_CXX_OVERLAY_SWIFT_COMPILE_FLAGS}