ART: Add FileNotFoundException to preloads for test 912

The JIT might load a class for exception handling.

Bug: 63581208
Test: art/test/testrunner/testrunner.py -b --host -t 912
Change-Id: Ifc812c88a59ebe779b29e0bb8846877e3799176f
diff --git a/test/912-classes/src-art/art/Test912.java b/test/912-classes/src-art/art/Test912.java
index 9896eac..fbf8794 100644
--- a/test/912-classes/src-art/art/Test912.java
+++ b/test/912-classes/src-art/art/Test912.java
@@ -228,7 +228,8 @@
     // The JIT may deeply inline and load some classes. Preload these for test determinism.
     final String PRELOAD_FOR_JIT[] = {
         "java.nio.charset.CoderMalfunctionError",
-        "java.util.NoSuchElementException"
+        "java.util.NoSuchElementException",
+        "java.io.FileNotFoundException",  // b/63581208
     };
     for (String s : PRELOAD_FOR_JIT) {
       Class.forName(s);