Enable import of _Concurrency by default on Linux

Author: drexin

cmake/modules/Libdispatch.cmake

@@ -101,6 +101,14 @@ foreach(sdk ${DISPATCH_SDKS})
                           # ensure that we strip out the DESTDIR environment
                           # from the sub-build
                           ${CMAKE_COMMAND} -E env --unset=DESTDIR ${CMAKE_COMMAND} --build . --target install
+                        COMMAND
+                          ${CMAKE_COMMAND} -E copy
+                          <INSTALL_DIR>/${LIBDISPATCH_RUNTIME_DIR}/${SWIFT_SDK_${sdk}_SHARED_LIBRARY_PREFIX}dispatch${SWIFT_SDK_${sdk}_SHARED_LIBRARY_SUFFIX}
+                          ${SWIFTLIB_DIR}/${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}/${SWIFT_SDK_${sdk}_SHARED_LIBRARY_PREFIX}dispatch${SWIFT_SDK_${sdk}_SHARED_LIBRARY_SUFFIX}
+                        COMMAND
+                          ${CMAKE_COMMAND} -E copy
+                          <INSTALL_DIR>/${LIBDISPATCH_RUNTIME_DIR}/${SWIFT_SDK_${sdk}_SHARED_LIBRARY_PREFIX}BlocksRuntime${SWIFT_SDK_${sdk}_SHARED_LIBRARY_SUFFIX}
+                          ${SWIFTLIB_DIR}/${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}/${SWIFT_SDK_${sdk}_SHARED_LIBRARY_PREFIX}BlocksRuntime${SWIFT_SDK_${sdk}_SHARED_LIBRARY_SUFFIX}
                         STEP_TARGETS
                           install
                         BUILD_BYPRODUCTS

lib/Frontend/Frontend.cpp

@@ -759,6 +759,8 @@ static bool shouldImportConcurrencyByDefault(const llvm::Triple &target) {
     return true;
   if (target.isOSWindows())
     return true;
+  if (target.isOSLinux())
+    return true;
   return false;
 }