Initial f2fs support

Need to add this to your source tree:
https://github.com/razrqcom-dev-team/android_external_f2fs-tools

Change-Id: I3ee9ebbb617259655518f8ea356ce7b8c246cd4d
diff --git a/prebuilt/Android.mk b/prebuilt/Android.mk
index 74923a0..39f702b 100644
--- a/prebuilt/Android.mk
+++ b/prebuilt/Android.mk
@@ -89,6 +89,11 @@
     RELINK_SOURCE_FILES += $(TARGET_RECOVERY_ROOT_OUT)/sbin/openaes
     RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libopenaes.so
 endif
+ifeq ($(TARGET_USERIMAGES_USE_F2FS), true)
+    RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/mkfs.f2fs
+    RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/fsck.f2fs
+    RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/fibmap.f2fs
+endif
 
 TWRP_AUTOGEN := $(intermediates)/teamwin