Fix testing setup

There were some problems with the existing testing setup:

 - Makefile rules for test-file compilation used CFLAGS instead of
   CXXFLAGS in makefile.unix

src/test/test_bitcoin.cpp

@@ -1,6 +1,16 @@
 #define BOOST_TEST_MODULE uint160
 #include <boost/test/unit_test.hpp>
 
+#include "../main.h"
+#include "../wallet.h"
+
 #include "uint160_tests.cpp"
 #include "uint256_tests.cpp"
 
+
+CWallet* pwalletMain;
+
+void Shutdown(void* parg)
+{
+	exit(0);
+}