Support to build vendor.img

Bug: 8341435
Change-Id: I2db7970936984d38aed35054e3f695d298f4e512
diff --git a/tools/releasetools/build_image.py b/tools/releasetools/build_image.py
index d5bd451..f8f2ada 100755
--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -128,6 +128,9 @@
   elif mount_point == "cache":
     copy_prop("cache_fs_type", "fs_type")
     copy_prop("cache_size", "partition_size")
+  elif mount_point == "vendor":
+    copy_prop("vendor_fs_type", "fs_type")
+    copy_prop("vendor_size", "partition_size")
 
   return d
 
@@ -164,6 +167,8 @@
     mount_point = "data"
   elif image_filename == "cache.img":
     mount_point = "cache"
+  elif image_filename == "vendor.img":
+    mount_point = "vendor"
   else:
     print >> sys.stderr, "error: unknown image file name ", image_filename
     exit(1)