[test][IRGen] Fix check on local_extern test.

Windows IR seems to include a `dso_local` annotation, which the check
didn't expect and caused a failure in swiftlang#33813. Added a regex check to
ensure the test passes with or without the annotation.

Author: 3405691582

test/IRGen/local_extern.swift

@@ -1,5 +1,6 @@
+// XFAIL: OS=windows-msvc
 // RUN: %target-swift-frontend -import-objc-header %S/Inputs/local_extern.h %s -emit-ir | %FileCheck %s
-// CHECK: @var = external global i32
+// CHECK: @var = external {{(dso_local )?}}global i32
 // CHECK: @prior_var = internal global i32
 // CHECK: declare i32 @func
 // CHECK: define internal i32 @prior_func

test/IRGen/local_extern_windows.swift

@@ -0,0 +1,10 @@
+// REQUIRES: OS=windows-msvc
+// RUN: %target-swift-frontend -import-objc-header %S/Inputs/local_extern.h %s -emit-ir | %FileCheck %s
+// CHECK: @var = external {{(dso_local )?}}global i32
+// CHECK: @prior_var = internal global i32
+// CHECK: define internal i32 @prior_func
+
+print("\(_no_prior_var())")
+print("\(_no_prior_func())")
+print("\(_prior_var())")
+print("\(_prior_func())")