util: Don't set strMiscWarning on every exception

Fixes bitcoin/bitcoin#6809 - run-of-the-mill exceptions should not get into
strMiscWarning (which is reported by `getinfo`).

src/util.cpp

@@ -449,7 +449,6 @@ void PrintExceptionContinue(const std::exception* pex, const char* pszThread)
     std::string message = FormatException(pex, pszThread);
     LogPrintf("\n\n************************\n%s\n", message);
     fprintf(stderr, "\n\n************************\n%s\n", message.c_str());
-    strMiscWarning = message;
 }
 
 boost::filesystem::path GetDefaultDataDir()