Added test for ifunc support in dynamic linker.

ifuncs now work in i386 and x86_64 when called in the same library as
well as in a different library.

Bug:6657325
(cherry picked from commit c5a13efa9bc4264be0a9a9e37c00633af01584ed)

Change-Id: I321d780bc2f9bd1baa749e1acacd2683aefe827b
diff --git a/tests/libs/dlopen_testlib_ifunc.c b/tests/libs/dlopen_testlib_ifunc.c
new file mode 100644
index 0000000..1c4bafa
--- /dev/null
+++ b/tests/libs/dlopen_testlib_ifunc.c
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+const char* foo() __attribute__ ((ifunc ("foo_ifunc")));
+
+const char* f1() {
+  return "unset";
+}
+
+const char* f2() {
+  return "set";
+}
+
+void* foo_ifunc() {
+   char* choice = getenv("IFUNC_CHOICE");
+   return choice == NULL ? f1 : f2;
+}
+
+const char* foo_library() {
+   return foo();
+}
\ No newline at end of file