Update test for LibraryEvolution feature

Author: DougGregor

test/Frontend/print-supported-features.swift

@@ -2,7 +2,8 @@
 
 // CHECK: "features": {
 // CHECK-NEXT:   "optional": [
-// CHECK: { "name": "StrictMemorySafety", "migratable": true, "categories": ["StrictMemorySafety"], "flag_name": "-strict-memory-safety" }
+// CHECK: { "name": "StrictMemorySafety", "migratable": true, "categories": ["StrictMemorySafety"], "flag_name": "-strict-memory-safety" },
+// CHECK: { "name": "LibraryEvolution", "flag_name": "-enable-library-evolution" }
 // CHECK-NEXT: ],
 // CHECK-NEXT:   "upcoming": [
 // CHECK:     { "name": "InferIsolatedConformances", "migratable": true, "categories": ["IsolatedConformances"], "enabled_in": "7" },