Add make_ext4fs to support installing apps to SD card

The default createSecureContainer format is changed from fat32 to ext4 in PackageHelper::CreateSdDir in:
/frameworks/base/core/java/com/android/internal/content/PackageHelper.java
We need to add make_ext4fs into the system image to support installing apps to SD card.
In kernel, we also need to add ext4 filesystem support.

Change-Id: If4817a95663144a6bfaeeed0c7cb081063a0daad
Signed-off-by: Jun Tian <jun.j.tian@intel.com>
Signed-off-by: Liang Chen <liang.l.chen@intel.com>
Signed-off-by: Panfeng Chang <panfengx.chang@intel.com>
diff --git a/target/product/core.mk b/target/product/core.mk
index 8a7d6df..87872d6 100644
--- a/target/product/core.mk
+++ b/target/product/core.mk
@@ -114,6 +114,7 @@
     libwebrtc_audio_preprocessing \
     libwilhelm \
     libz \
+    make_ext4fs \
     mdnsd \
     requestsync \
     screencap \