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/Android.mk b/runtime/Android.mk
index 8d532c7..52b5f43 100644
--- a/runtime/Android.mk
+++ b/runtime/Android.mk
@@ -158,6 +158,7 @@
 
 LIBART_COMMON_SRC_FILES += \
 	arch/context.cc \
+	arch/memcmp16.cc \
 	arch/arm/registers_arm.cc \
 	arch/arm64/registers_arm64.cc \
 	arch/x86/registers_x86.cc \
@@ -209,6 +210,7 @@
 	arch/arm/context_arm.cc.arm \
 	arch/arm/entrypoints_init_arm.cc \
 	arch/arm/jni_entrypoints_arm.S \
+	arch/arm/memcmp16_arm.S \
 	arch/arm/portable_entrypoints_arm.S \
 	arch/arm/quick_entrypoints_arm.S \
 	arch/arm/arm_sdiv.S \
@@ -254,6 +256,7 @@
 	arch/mips/context_mips.cc \
 	arch/mips/entrypoints_init_mips.cc \
 	arch/mips/jni_entrypoints_mips.S \
+	arch/mips/memcmp16.S \
 	arch/mips/portable_entrypoints_mips.S \
 	arch/mips/quick_entrypoints_mips.S \
 	arch/mips/thread_mips.cc \