[test] Fix mangled name for renamed test.

Author: jrose-apple

test/DebugInfo/ErrorVar.swift

@@ -11,7 +11,7 @@ enum MyError : Error {
 // thrown error we create a shadow stack location holding the address of the
 // location that holds the pointer to the error instead.
 func simple(_ placeholder: Int64) throws -> () {
-  // CHECK: define {{.*}}void @_T06Errors6simpleys5Int64VKF(i64, %swift.refcounted* swiftself, %swift.error**)
+  // CHECK: define {{.*}}void @_T08ErrorVar6simpleys5Int64VKF(i64, %swift.refcounted* swiftself, %swift.error**)
   // CHECK: call void @llvm.dbg.declare
   // CHECK: call void @llvm.dbg.declare({{.*}}, metadata ![[ERROR:[0-9]+]], metadata ![[DEREF:[0-9]+]])
   // CHECK: ![[ERROR]] = !DILocalVariable(name: "$error", arg: 2,