Add SSE optmized IDCT in JPEG decoding for INTEL Atom platform.

ADD SSE optmized IDCT. It makes album2D workload about 18%
faster than jidctfst.c. The major implementation is at
"jidctintelsse.c".

Change-Id: I6dc6f367158172b468e85e7eae249027eb1766cf
diff --git a/Android.mk b/Android.mk
index 2670652..6861006 100644
--- a/Android.mk
+++ b/Android.mk
@@ -30,8 +30,13 @@
 # enable tile based decode
 LOCAL_CFLAGS += -DANDROID_TILE_BASED_DECODE
 
+ifeq ($(TARGET_ARCH_VARIANT),x86-atom)
+LOCAL_CFLAGS += -DANDROID_INTELSSE2_IDCT
+LOCAL_SRC_FILES += jidctintelsse.c
+else
 # enable armv6 idct assembly
 LOCAL_CFLAGS += -DANDROID_ARMV6_IDCT
+endif
 
 LOCAL_MODULE:= libjpeg