build: Add --disable-bip70 configure option

This patch adds a --disable-bip70 configure option that disables BIP70
payment request support. When disabled, this removes the dependency of
the GUI on OpenSSL and Protobuf.

src/qt/coincontroldialog.cpp

@@ -2,10 +2,15 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
 #include <qt/coincontroldialog.h>
 #include <qt/forms/ui_coincontroldialog.h>
 
 #include <qt/addresstablemodel.h>
+#include <base58.h>
 #include <qt/bitcoinunits.h>
 #include <qt/guiutil.h>
 #include <qt/optionsmodel.h>