swift-lang: shuffle the source directory structure (NFC)

This moves the swift-lang library out of the tools/SourceKit directory
and into the stdlib directory.  As it stands, the library required that
the standard library and the SDK overlay was being built.  This is
implicitly done when building the stdlib subdirectory.  Furthermore, it
had an odd tie between the flags for Swift and SourceKit which now have
the logic separated.  This clearly delineates the host and target
components in the repository.

stdlib/tools/CMakeLists.txt

@@ -1,3 +1,11 @@
 if(SWIFT_BUILD_DYNAMIC_STDLIB AND SWIFT_INCLUDE_TESTS)
   add_subdirectory(swift-reflection-test)
 endif()
+if(SWIFT_BUILD_SDK_OVERLAY)
+  include(CheckIncludeFiles)
+  check_include_files("xpc/xpc.h" HAVE_XPC_H)
+
+  if(SWIFT_BUILD_SOURCEKIT AND CMAKE_SYSTEM_NAME STREQUAL Darwin AND HAVE_XPC_H)
+    add_subdirectory(swift-lang)
+  endif()
+endif()

stdlib/tools/swift-lang/CMakeLists.txt

@@ -0,0 +1,27 @@
+if(SWIFT_HOST_VARIANT MATCHES "^iphoneos")
+  set(SWIFT_LANG_TARGET_SDK "IOS")
+elseif(SWIFT_HOST_VARIANT MATCHES "^iphonesimulator")
+  set(SWIFT_LANG_TARGET_SDK "IOS_SIMULATOR")
+elseif(SWIFT_HOST_VARIANT MATCHES "^macosx")
+  set(SWIFT_LANG_TARGET_SDK "OSX")
+else()
+  message(SEND_ERROR "Unknown SDK for SwiftLang")
+endif()
+
+add_swift_target_library(swiftSwiftLang SHARED
+  SwiftLang.swift
+  SourceKitdClient.swift
+  SourceKitdRequest.swift
+  SourceKitdResponse.swift
+  SourceKitdUID.swift
+
+  GYB_SOURCES
+    UIDs.swift.gyb
+
+  SWIFT_MODULE_DEPENDS_OSX Darwin Foundation
+  PRIVATE_LINK_LIBRARIES sourcekitd
+  SWIFT_COMPILE_FLAGS -F${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib
+  INSTALL_IN_COMPONENT sourcekit-xpc-service
+  DARWIN_INSTALL_NAME_DIR "@rpath"
+  TARGET_SDKS ${SWIFT_LANG_TARGET_SDK}
+  IS_STDLIB)

tools/SourceKit/tools/CMakeLists.txt

@@ -10,4 +10,3 @@ if(LibEdit_FOUND AND LibEdit_HAS_UNICODE)
   add_swift_tool_subdirectory(sourcekitd-repl)
 endif()
 add_swift_tool_subdirectory(complete-test)
-add_subdirectory(swift-lang)

tools/SourceKit/tools/swift-lang/CMakeLists.txt

@@ -1,31 +0,0 @@
-if(NOT SWIFT_SOURCEKIT_USE_INPROC_LIBRARY AND SWIFT_BUILD_STDLIB AND SWIFT_BUILD_SDK_OVERLAY)
-  # The build type of swiftlang should agree with stdlib
-  # This setting could avoid us adding additional search paths when building
-  # executables using SwiftLang.
-  set(SWIFT_LANG_LIBRARY_BUILD_TYPES)
-  if(SWIFT_BUILD_DYNAMIC_STDLIB)
-    list(APPEND SWIFT_LANG_LIBRARY_BUILD_TYPES SHARED)
-  endif()
-  if(SWIFT_BUILD_STATIC_STDLIB)
-    list(APPEND SWIFT_LANG_LIBRARY_BUILD_TYPES STATIC)
-  endif()
-
-  add_swift_target_library(swiftSwiftLang ${SWIFT_LANG_LIBRARY_BUILD_TYPES}
-    SwiftLang.swift
-    SourceKitdClient.swift
-    SourceKitdRequest.swift
-    SourceKitdResponse.swift
-    SourceKitdUID.swift
-
-    GYB_SOURCES
-      UIDs.swift.gyb
-
-    DEPENDS sourcekitd-test
-    SWIFT_MODULE_DEPENDS_OSX Darwin Foundation
-    PRIVATE_LINK_LIBRARIES sourcekitd
-    SWIFT_COMPILE_FLAGS -F${SWIFT_LIBRARY_OUTPUT_INTDIR}
-    INSTALL_IN_COMPONENT sourcekit-xpc-service
-    DARWIN_INSTALL_NAME_DIR "@rpath"
-    TARGET_SDKS ${SOURCEKIT_DEFAULT_TARGET_SDK}
-    IS_STDLIB)
-endif()