[windows] Adapt test to pass on Windows.

The underscores weren't printed while compiling for Windows between the
symbolic and the mangled name tokens. Make the underscores optional, to
allow the test pass on Windows.

Author: drodriguez

test/IRGen/opaque_result_type_private_underlying.swift

@@ -10,18 +10,18 @@
 import Repo1
 #endif
 
-// SINGLEMODULE: s37opaque_result_type_private_underlying18UsePublicInlinableVAA1AAAMA" = internal constant { {{.*}}symbolic _____ 37opaque_result_type_private_underlying7PublicSV
-// NONRESILIENT: s37opaque_result_type_private_underlying18UsePublicInlinableV5Repo11AAAMA" = internal constant { {{.*}}symbolic _____ 5Repo17PublicSV
-// RESILIENT: s37opaque_result_type_private_underlying18UsePublicInlinableV5Repo11AAAMA" = internal constant { {{.*}}symbolic _____ 5Repo17PublicSV
+// SINGLEMODULE: s37opaque_result_type_private_underlying18UsePublicInlinableVAA1AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}37opaque_result_type_private_underlying7PublicSV
+// NONRESILIENT: s37opaque_result_type_private_underlying18UsePublicInlinableV5Repo11AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}5Repo17PublicSV
+// RESILIENT: s37opaque_result_type_private_underlying18UsePublicInlinableV5Repo11AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}5Repo17PublicSV
 public struct UsePublicInlinable : A {
   public init() {}
   public func bindAssoc() -> some Q {
     return PublicUnderlyingInlinable().bindAssoc()
   }
 }
 
-// SINGLEMODULE: s37opaque_result_type_private_underlying9UsePublicVAA1AAAMA" = internal constant { {{.*}}symbolic _____ 37opaque_result_type_private_underlying7PublicSV
-// NONRESILIENT: s37opaque_result_type_private_underlying9UsePublicV5Repo11AAAMA" = internal constant { {{.*}}symbolic _____ 5Repo17PublicSV
+// SINGLEMODULE: s37opaque_result_type_private_underlying9UsePublicVAA1AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}37opaque_result_type_private_underlying7PublicSV
+// NONRESILIENT: s37opaque_result_type_private_underlying9UsePublicV5Repo11AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}5Repo17PublicSV
 // RESILIENT: s37opaque_result_type_private_underlying9UsePublicV5Repo11AAAMA" = internal constant {  {{.*}}symbolic _____y_Qo_ 5Repo116PublicUnderlyingV9bindAssocQryFQO
 public struct UsePublic : A {
   public init() {}
@@ -30,7 +30,7 @@ public struct UsePublic : A {
   }
 }
 
-// SINGLEMODULE: s37opaque_result_type_private_underlying11UseInternalVAA1AAAMA" = internal constant { {{.*}}symbolic _____ 37opaque_result_type_private_underlying9InternalSV
+// SINGLEMODULE: s37opaque_result_type_private_underlying11UseInternalVAA1AAAMA" = internal constant { {{.*}}symbolic {{(_____ )?}}37opaque_result_type_private_underlying9InternalSV
 // NONRESILIENT: s37opaque_result_type_private_underlying11UseInternalV5Repo11AAAMA" = internal constant { {{.*}}symbolic _____y_Qo_ 5Repo118InternalUnderlyingV9bindAssocQryFQO
 // RESILIENT: s37opaque_result_type_private_underlying11UseInternalV5Repo11AAAMA" = internal constant { {{.*}}symbolic _____y_Qo_ 5Repo118InternalUnderlyingV9bindAssocQryFQO
 public struct UseInternal: A {