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/compiler/oat_test.cc b/compiler/oat_test.cc
index 49cf71b..0b7272c 100644
--- a/compiler/oat_test.cc
+++ b/compiler/oat_test.cc
@@ -180,7 +180,7 @@
   EXPECT_EQ(80U, sizeof(OatHeader));
   EXPECT_EQ(8U, sizeof(OatMethodOffsets));
   EXPECT_EQ(24U, sizeof(OatQuickMethodHeader));
-  EXPECT_EQ(79 * GetInstructionSetPointerSize(kRuntimeISA), sizeof(QuickEntryPoints));
+  EXPECT_EQ(78 * GetInstructionSetPointerSize(kRuntimeISA), sizeof(QuickEntryPoints));
 }
 
 TEST_F(OatTest, OatHeaderIsValid) {