Mark another thorough String test as requiring an optimized stdlib (#22043)
This one's taking a pretty long time on simulators, only sometimes
making it under the timeout limit.
rdar://problem/46736948
(cherry picked from commit a628d5d76a213ed150e7f371c086b3b44aa88c44)
diff --git a/validation-test/stdlib/StringNormalization.swift b/validation-test/stdlib/StringNormalization.swift
index edaf495..0126a56 100644
--- a/validation-test/stdlib/StringNormalization.swift
+++ b/validation-test/stdlib/StringNormalization.swift
@@ -21,6 +21,7 @@
// RUN: %target-run %t/a.out %S/Inputs/NormalizationTest.txt
// REQUIRES: executable_test
// REQUIRES: objc_interop
+// REQUIRES: optimized_stdlib
import Swift
import StdlibUnittest