recovery: Dump the signature in the zip package.

We have been occasionally seeing "signature verification failed" error
message when applying an update. Make more verbose output to help
debugging.

Bug: 28246534
Change-Id: Id83633adc9b86b3fd36abbb504e430f0816f12e4
diff --git a/print_sha1.h b/print_sha1.h
index fa3d7e0..c7c1f36 100644
--- a/print_sha1.h
+++ b/print_sha1.h
@@ -22,7 +22,7 @@
 
 #include "openssl/sha.h"
 
-static std::string print_sha1(const uint8_t sha1[SHA_DIGEST_LENGTH], size_t len) {
+static std::string print_sha1(const uint8_t* sha1, size_t len) {
     const char* hex = "0123456789abcdef";
     std::string result = "";
     for (size_t i = 0; i < len; ++i) {
@@ -40,4 +40,8 @@
     return print_sha1(sha1, 4);
 }
 
+static std::string print_hex(const uint8_t* bytes, size_t len) {
+  return print_sha1(bytes, len);
+}
+
 #endif  // RECOVERY_PRINT_SHA1_H