Can't log to debug log before chain params initialized

Add a function `AreBaseParamsConfigured` and use this to check
before writing to the debug log. This avoids assertions when the
application happens to log too early, which happens in the GUI.

Messages logged before the base parameters are configured can be
shown using `-printtoconsole`.

src/chainparamsbase.cpp

@@ -91,3 +91,7 @@ bool SelectBaseParamsFromCommandLine() {
     }
     return true;
 }
+
+bool AreBaseParamsConfigured() {
+    return pCurrentBaseParams != NULL;
+}

src/chainparamsbase.h

@@ -49,4 +49,10 @@ void SelectBaseParams(CBaseChainParams::Network network);
  */
 bool SelectBaseParamsFromCommandLine();
 
+/**
+ * Return true if SelectBaseParamsFromCommandLine() has been called to select
+ * a network.
+ */
+bool AreBaseParamsConfigured();
+
 #endif

src/util.cpp

@@ -205,7 +205,7 @@ int LogPrintStr(const std::string &str)
         // print to console
         ret = fwrite(str.data(), 1, str.size(), stdout);
     }
-    else if (fPrintToDebugLog)
+    else if (fPrintToDebugLog && AreBaseParamsConfigured())
     {
         static bool fStartedNewLine = true;
         boost::call_once(&DebugPrintInit, debugPrintInitFlag);