Mark shared global vals to fix K/N worker thread crash

(cherry picked from commit e346f0c5c0fb138cdf4a506e4e7f61234d60d10e)

runtime/src/main/kotlin/kotlin/text/Strings.kt

@@ -5,6 +5,8 @@
 
 package kotlin.text
 
+import kotlin.native.concurrent.SharedImmutable
+
 /**
  * Returns the index within this string of the first occurrence of the specified character, starting from the specified offset.
  */
@@ -336,6 +338,7 @@ public actual fun String.compareTo(other: String, ignoreCase: Boolean): Int {
     else compareToIgnoreCase(this, other)
 }
 
+@SharedImmutable
 private val STRING_CASE_INSENSITIVE_ORDER = Comparator<String> { a, b -> a.compareTo(b, ignoreCase = true) }
 
 public actual val String.Companion.CASE_INSENSITIVE_ORDER: Comparator<String>