dumpkey: add back to build for zip verification support

Change-Id: I2cdf10e94b45a27ef58f9d915efc1f42305ccd9f
diff --git a/tools/dumpkey/DumpPublicKey.mf b/tools/dumpkey/DumpPublicKey.mf
new file mode 100644
index 0000000..7bb3bc8
--- /dev/null
+++ b/tools/dumpkey/DumpPublicKey.mf
@@ -0,0 +1 @@
+Main-Class: com.android.dumpkey.DumpPublicKey