Rewrote enum lowering to support usage from other modules.

- Split up enum lowering into two stages: descriptors creation and IR creation.
- Added link stage test.
- Enum.valueOf() uses binary search instead of linear.

runtime/src/main/kotlin/konan/internal/RuntimeUtils.kt

@@ -27,15 +27,26 @@ fun ThrowNoWhenBranchMatchedException(): Nothing {
 @ExportForCppRuntime
 internal fun TheEmptyString() = ""
 
-fun <T: Enum<T>> valueOfForEnum(name: String, arr: Array<T>) : T
+fun <T: Enum<T>> valueOfForEnum(name: String, values: Array<T>) : T
 {
-    for (x in arr)
-        if (x.name == name)
-            return x
+    var left = 0
+    var right = values.size - 1
+    while (left <= right) {
+        val middle = (left + right) / 2
+        val x = values[middle].name.compareTo(name)
+        when {
+            x < 0 -> left = middle + 1
+            x > 0 -> right = middle - 1
+            else -> return values[middle]
+        }
+    }
     throw Exception("Invalid enum name: $name")
 }
 
 fun <T: Enum<T>> valuesForEnum(values: Array<T>): Array<T>
 {
-    return values.clone() as Array<T>
+    val result = Array<T?>(values.size, { null })
+    for (value in values)
+        result[value.ordinal] = value
+    return result as Array<T>
 }