Disable frexp and modf for half

http://b/23536224
http://b/26099914

Variants of frexp and modf for half vectors also fail instruction
selection on AArch64.  Disable this test until we update on-device LLVM.

Change-Id: I0a7463c8c955f7bd945b5ec7690d2a4a158579dc
(cherry picked from commit de10692c7e41bb52ccc627dd85e1e3f35d85ffb6)
diff --git a/java/tests/RsTest/src/com/android/rs/test/math_fp16.rs b/java/tests/RsTest/src/com/android/rs/test/math_fp16.rs
index e53ddd6..9c631a7 100644
--- a/java/tests/RsTest/src/com/android/rs/test/math_fp16.rs
+++ b/java/tests/RsTest/src/com/android/rs/test/math_fp16.rs
@@ -131,7 +131,12 @@
     //
     // TEST_HN_FUNC_HN(fract);
     TEST_HN_FUNC_HN_PHN(fract);
-    TEST_HN_FUNC_HN_PIN(frexp);
+    // Bug: https://b.corp.google.com/issues/26099914
+    // This test is broken due to an LLVM issue that has since been fixed.
+    // Enable this test once on-device LLVM and RenderScript prebuilts get
+    // udpated.
+    //
+    // TEST_HN_FUNC_HN_PIN(frexp);
 
     TEST_HN_FUNC_HN_HN(hypot);
     TEST_IN_FUNC_HN(ilogb);
@@ -153,7 +158,12 @@
     TEST_HN_FUNC_HN_H(min);
     TEST_HN_FUNC_HN_HN_HN(mix);
     TEST_HN_FUNC_HN_HN_H(mix);
-    TEST_HN_FUNC_HN_PHN(modf);
+    // Bug: https://b.corp.google.com/issues/26099914
+    // This test is broken due to an LLVM issue that has since been fixed.
+    // Enable this test once on-device LLVM and RenderScript prebuilts get
+    // udpated.
+    //
+    // TEST_HN_FUNC_HN_PHN(modf);
 
     h1 = nan_half();