ART: Move __memcmp16 from Bionic to ART

Handle __memcmp16 / MemCmp16 in ART. Import assembly implementations
for arm and mips from Bionic. Use a generic C version for all other
platforms.

Removes the memcmp16 quick entrypoint, as it is never used. Bump
the oat version and update thread.cc and checks to reflect the
structural change.

Change-Id: I54a5a1da2a0a43ef271c8aeda0bf2276b8b11ac6
diff --git a/runtime/entrypoints_order_test.cc b/runtime/entrypoints_order_test.cc
index f33befb..0dd33cf 100644
--- a/runtime/entrypoints_order_test.cc
+++ b/runtime/entrypoints_order_test.cc
@@ -233,8 +233,7 @@
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pShlLong, pShrLong, kPointerSize);
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pShrLong, pUshrLong, kPointerSize);
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pUshrLong, pIndexOf, kPointerSize);
-    EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pIndexOf, pMemcmp16, kPointerSize);
-    EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pMemcmp16, pStringCompareTo, kPointerSize);
+    EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pIndexOf, pStringCompareTo, kPointerSize);
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pStringCompareTo, pMemcpy, kPointerSize);
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pMemcpy, pQuickImtConflictTrampoline, kPointerSize);
     EXPECT_OFFSET_DIFFNP(QuickEntryPoints, pQuickImtConflictTrampoline, pQuickResolutionTrampoline,