[build-script] Forward --skip-local-build to build-script-impl

Otherwise, build-script-impl ignores --skip-local-build.

Author: vedantk

utils/build-script

@@ -552,6 +552,8 @@ class BuildScriptInvocation(object):
             impl_args += ["--long-test"]
         if args.stress_test:
             impl_args += ["--stress-test"]
+        if args.skip_local_build:
+            impl_args += ["--skip-local-build"]
         if args.only_executable_test:
             impl_args += ["--only-executable-test"]
         if not args.benchmark:

validation-test/BuildSystem/skip-local-build.test-sh

@@ -0,0 +1,6 @@
+# RUN: %swift_src_root/utils/build-script --dump-config --skip-local-build 2>&1 | %FileCheck %s -check-prefix=CONFIG
+# CONFIG: "skip_local_build": true
+
+# RUN: %swift_src_root/utils/build-script --dry-run --verbose-build --skip-local-build 2>&1 | %FileCheck %s -check-prefix=DRY
+# DRY: build-script-impl
+# DRY-SAME: --skip-local-build