message: refactor: Replace RecursiveMutex with Mutex in warnings.cpp
diff: #include <util/system.h>
  #include <util/translation.h>
  -static RecursiveMutex cs_warnings;
  -static std::string strMiscWarning GUARDED_BY(cs_warnings);
  -static bool fLargeWorkForkFound GUARDED_BY(cs_warnings) = false;
  -static bool fLargeWorkInvalidChainFound GUARDED_BY(cs_warnings) = false;
  +static Mutex g_warnings_mutex;
  +static std::string strMiscWarning GUARDED_BY(g_warnings_mutex);
  +static bool fLargeWorkForkFound GUARDED_BY(g_warnings_mutex) = false;
  +static bool fLargeWorkInvalidChainFound GUARDED_BY(g_warnings_mutex) = false;
  std::string strMintWarning;
  void SetMiscWarning(const std::string& strWarning)
  {
  - LOCK(cs_warnings);
  + LOCK(g_warnings_mutex);
  strMiscWarning = strWarning;
  }
  void SetfLargeWorkForkFound(bool flag)
  {
  - LOCK(cs_warnings);
  + LOCK(g_warnings_mutex);
  fLargeWorkForkFound = flag;
  }
  bool GetfLargeWorkForkFound()
  {
  - LOCK(cs_warnings);
  + LOCK(g_warnings_mutex);
  return fLargeWorkForkFound;
  }
  void SetfLargeWorkInvalidChainFound(bool flag)
  {
  - LOCK(cs_warnings);
  + LOCK(g_warnings_mutex);
  fLargeWorkInvalidChainFound = flag;
  }
  @@ -46,7 +46,7 @@ std::string GetWarnings(bool verbose)
  std::string warnings_verbose;
  const std::string warning_separator = "<hr />";
  - LOCK(cs_warnings);
  + LOCK(g_warnings_mutex);
  // Pre-release build warning
  if (!CLIENT_VERSION_IS_RELEASE) {
  