[build] Respect DEPLOYMENT_VERSION_{IOS|TVOS|WATCHOS} for Simulator targets

This makes sure that Cxx and CxxStdlib modules are built with consistent deployment targets for iOS Simulator and iOS Device.

rdar://141232269
(cherry picked from commit d1a435c)

Author: egorzhdan

stdlib/cmake/modules/SwiftSource.cmake

@@ -248,13 +248,13 @@ function(_add_target_variant_swift_compile_flags
     if("${sdk}" STREQUAL "OSX" AND DEFINED VARIANT_DEPLOYMENT_VERSION_OSX)
       set(sdk_deployment_version ${VARIANT_DEPLOYMENT_VERSION_OSX})
     endif()
-    if("${sdk}" STREQUAL "IOS" AND DEFINED VARIANT_DEPLOYMENT_VERSION_IOS)
+    if(("${sdk}" STREQUAL "IOS" OR "${sdk}" STREQUAL "IOS_SIMULATOR") AND DEFINED VARIANT_DEPLOYMENT_VERSION_IOS)
       set(sdk_deployment_version ${VARIANT_DEPLOYMENT_VERSION_IOS})
     endif()
-    if("${sdk}" STREQUAL "TVOS" AND DEFINED VARIANT_DEPLOYMENT_VERSION_TVOS)
+    if(("${sdk}" STREQUAL "TVOS" OR "${sdk}" STREQUAL "TVOS_SIMULATOR") AND DEFINED VARIANT_DEPLOYMENT_VERSION_TVOS)
       set(sdk_deployment_version ${VARIANT_DEPLOYMENT_VERSION_TVOS})
     endif()
-    if("${sdk}" STREQUAL "WATCHOS" AND DEFINED VARIANT_DEPLOYMENT_VERSION_WATCHOS)
+    if(("${sdk}" STREQUAL "WATCHOS" OR "${sdk}" STREQUAL "WATCHOS_SIMULATOR") AND DEFINED VARIANT_DEPLOYMENT_VERSION_WATCHOS)
       set(sdk_deployment_version ${VARIANT_DEPLOYMENT_VERSION_WATCHOS})
     endif()
 

test/Interop/Cxx/stdlib/overlay-backdeployment-ios-simulator.swift

@@ -0,0 +1,7 @@
+// RUN: %swift -c %s -cxx-interoperability-mode=default -target arm64-apple-ios7.0-simulator
+
+// REQUIRES: DARWIN_SIMULATOR=ios
+
+import Cxx
+
+public func takesCxxType(_ s: some CxxSequence) {}

test/Interop/Cxx/stdlib/overlay-backdeployment-ios.swift

@@ -0,0 +1,7 @@
+// RUN: %swift -c %s -cxx-interoperability-mode=default -target arm64-apple-ios7.0
+
+// REQUIRES: OS=ios
+
+import Cxx
+
+public func takesCxxType(_ s: some CxxSequence) {}