Fix leak on real output when using a very recent output

The wallet and the daemon applied different height considerations
when selecting outputs to use. This can leak information on which
input in a ring signature is the real one.

Found and originally fixed by smooth on Aeon.

src/cryptonote_config.h

@@ -45,6 +45,7 @@
 #define CURRENT_BLOCK_MAJOR_VERSION                     1
 #define CURRENT_BLOCK_MINOR_VERSION                     0
 #define CRYPTONOTE_BLOCK_FUTURE_TIME_LIMIT              60*60*2
+#define CRYPTONOTE_DEFAULT_TX_SPENDABLE_AGE             10
 
 #define BLOCKCHAIN_TIMESTAMP_CHECK_WINDOW               60