Merge pull request swiftlang#23608 from atrick/fix-build-script

build-script fix for --extra-swift-args.

Author: atrick

utils/build-script

@@ -763,8 +763,8 @@ class BuildScriptInvocation(object):
         # add them as one command.
         if args.extra_swift_args:
             impl_args += [
-                "--extra-swift-args",
-                ";".join(args.extra_swift_args)]
+                "--extra-swift-args=%s" % ';'.join(args.extra_swift_args)
+            ]
 
         # If we have extra_cmake_options, combine all of them together and then
         # add them as one command.