Build Runtime in macOS PR testing

For this to work, add the dependency on Darwin and start building the
Cxx Interop libraries.

Addresses rdar://160774928

Author: edymtt

CMakeLists.txt

@@ -1700,7 +1700,8 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_CXX_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
-          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE)
+          -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE
+          -DSwiftOverlay_ENABLE_CXX_INTEROP=TRUE)
 
       ExternalProject_Add("${stdlib_target}-Supplemental"
         SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/Runtimes/Supplemental"
@@ -1711,7 +1712,7 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
         # To ensure incremental builds work as expected
         BUILD_ALWAYS 1
         CMAKE_ARGS
-          -DSwift_ENABLE_RUNTIMES=StringProcessing|Synchronization|Distributed|Observation
+          -DSwift_ENABLE_RUNTIMES=StringProcessing|Synchronization|Distributed|Observation|Runtime
           -DBUILD_SHARED_LIBS=YES
           -DCMAKE_Swift_COMPILER_WORKS:BOOLEAN=YES
           -DCMAKE_BUILD_TYPE:STRING=${CMAKE_BUILD_TYPE}
@@ -1722,6 +1723,7 @@ if(SWIFT_ENABLE_NEW_RUNTIME_BUILD)
           -DCMAKE_Swift_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_C_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_CXX_COMPILER_TARGET:STRING=${stdlib_target_triple}
+          -DCMAKE_ASM_COMPILER_TARGET:STRING=${stdlib_target_triple}
           -DCMAKE_COLOR_DIAGNOSTICS:BOOLEAN=${CMAKE_COLOR_DIAGNOSTICS}
           -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
           -DCMAKE_FIND_PACKAGE_PREFER_CONFIG=TRUE)

Runtimes/Supplemental/Runtime/CMakeLists.txt

@@ -43,7 +43,7 @@ set(${PROJECT_NAME}_VENDOR_MODULE_DIR "${CMAKE_SOURCE_DIR}/../cmake/modules/vend
 
 find_package(SwiftCore REQUIRED)
 find_package(SwiftOverlay REQUIRED)
-#find_package(SwiftDarwin)
+find_package(SwiftDarwin)
 
 include(GNUInstallDirs)
 
@@ -154,7 +154,7 @@ target_link_libraries(swiftRuntime PRIVATE
   swift_Concurrency
   swiftCxxStdlib
   $<$<PLATFORM_ID:Android>:swiftAndroid>
-  #$<$<PLATFORM_ID:Darwin>:swiftDarwin>
+  $<$<PLATFORM_ID:Darwin>:swiftDarwin>
   $<$<PLATFORM_ID:Linux>:swiftGlibc>
   $<$<PLATFORM_ID:Windows>:swiftWinSDK>)