Add ozip decryption for Oppo/Realme device

This function will automatically decrypt .ozip file in a .zip and it will
save the .zip in the same folder of the .ozip and with the same name.
After the decryption, the flash will start.

To enable this function you have to set a Boardconfig flag with the
decryption key like i did here:

https://github.com/mauronofrio/android_device_realme_RMX1901/commit/a30625f80a31b9b85e4948fc9f9beeb61d5bcb8a

Original projects:
https://github.com/sabpprook/ozip2zip
https://github.com/bkerler/oppo_ozip_decrypt

Change-Id: Ic93243a565008c442bcf2992069b2801532ac7c1
diff --git a/prebuilt/Android.mk b/prebuilt/Android.mk
index 2935113..a4f6f2e 100644
--- a/prebuilt/Android.mk
+++ b/prebuilt/Android.mk
@@ -59,6 +59,9 @@
 RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/tune2fs
 RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/resize2fs
 RELINK_SOURCE_FILES += $(TARGET_RECOVERY_ROOT_OUT)/sbin/simg2img
+ifneq ($(TW_OZIP_DECRYPT_KEY),)
+    RELINK_SOURCE_FILES += $(TARGET_RECOVERY_ROOT_OUT)/sbin/ozip_decrypt
+endif
 ifneq ($(TARGET_ARCH), x86_64)
     RELINK_SOURCE_FILES += $(TARGET_OUT_EXECUTABLES)/linker
 endif