build: Remove dependency of bitcoin-cli on secp256k1

bitcoin-cli (in contrast to bitcoin-tx, which does signing ops)
shouldn't need secp256k1, and indeed it doesn't.

src/Makefile.am

@@ -361,8 +361,7 @@ endif
 bitcoin_cli_LDADD = \
   $(LIBBITCOIN_CLI) \
   $(LIBBITCOIN_UNIVALUE) \
-  $(LIBBITCOIN_UTIL) \
+  $(LIBBITCOIN_UTIL)
-  $(LIBSECP256K1)
 
 bitcoin_cli_LDADD += $(BOOST_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(EVENT_LIBS)
 #