Add apksigner to otatools.zip

BUG: 157735036
Test: Local build.
Change-Id: I3778021f94236b0ac09a33149f2872fb5f740be2
Merged-In: I95c7001ad520d6b4a415d21ffdef55152b0e82b2
diff --git a/core/Makefile b/core/Makefile
index 3da8d3a..47f4605 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -4059,6 +4059,7 @@
 INTERNAL_OTATOOLS_MODULES := \
   aapt2 \
   add_img_to_target_files \
+  apksigner \
   append2simg \
   avbtool \
   blk_alloc_to_base_fs \