x86: Enable KVM mode for Android x86 emulator (update/rebase)

This patch enables KVM mode on x86 Linux to boost performance of x86 emulaiton
if the hardware-based virtualization feature is present on the host machine.

Change-Id: I4b24474b3ec115a3b9a7bf017801f4f610253b09
Signed-off-by: Xiaohui Xin <xiaohui.xin@intel.com>
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
diff --git a/Makefile.target b/Makefile.target
index 7b7c1bc..fa76ed7 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -170,6 +170,15 @@
 LOCAL_SRC_FILES += fpu/softfloat-native.c
 endif
 
+# compile KVM only if target is x86 on x86 Linux
+ifeq ($(QEMU_HOST_TAG)-$(EMULATOR_TARGET_ARCH),linux-x86-x86)
+# the following is to include linux/kvm.h
+LOCAL_CFLAGS += -I /usr/include
+LOCAL_SRC_FILES += \
+    target-i386/kvm.c \
+    kvm-all.c
+endif
+
 ##############################################################################
 # Memory-access checking support.
 # Memory access checker uses information collected by instrumented code in