Suppress output when running unit tests.

This does two things:
1) Now does not output to debug.log if -printtodebugger flag is passed
2) Unit tests set -printtodebugger so only test results are output to stdout

Note that -printtodebugger only actually prints to the debugger on Windows.

src/test/test_bitcoin.cpp

@@ -13,7 +13,7 @@ extern void noui_connect();
 
 struct TestingSetup {
     TestingSetup() {
-        fPrintToConsole = true; // don't want to write to debug.log file
+        fPrintToDebugger = true; // don't want to write to debug.log file
         noui_connect();
         bitdb.MakeMock();
         LoadBlockIndex(true);