Add libbase to otatools

build_verity_tree uses libbase since b104044.

Change-Id: I6d3406a107ceb6cd58d1a51aa79935209d4c435f
diff --git a/core/Makefile b/core/Makefile
index 350666f..c930311 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1529,7 +1529,8 @@
   $(HOST_LIBRARY_PATH)/libevent-host$(HOST_SHLIB_SUFFIX) \
   $(HOST_LIBRARY_PATH)/libprotobuf-cpp-lite$(HOST_SHLIB_SUFFIX) \
   $(HOST_LIBRARY_PATH)/libssl-host$(HOST_SHLIB_SUFFIX) \
-  $(HOST_LIBRARY_PATH)/libz-host$(HOST_SHLIB_SUFFIX)
+  $(HOST_LIBRARY_PATH)/libz-host$(HOST_SHLIB_SUFFIX) \
+  $(HOST_LIBRARY_PATH)/libbase$(HOST_SHLIB_SUFFIX)
 
 .PHONY: otatools
 otatools: $(OTATOOLS)