message: ResolveBreakpointSite: fix outdated warning message
  Currently if a breakpoint site is already present, its ID will be returned, not the LLDB_INVALID_BREAK_ID.
  On the other hand, Process::CreateBreakpointSite may have another reasons to return LLDB_INVALID_BREAK_ID.
diff: @@ -454,13 +454,11 @@ bool BreakpointLocation::ResolveBreakpointSite() {
  if (new_id == LLDB_INVALID_BREAK_ID) {
  Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_BREAKPOINTS);
  if (log)
  - log->Warning("Tried to add breakpoint site at 0x%" PRIx64
  - " but it was already present.\n",
  + log->Warning("Failed to add breakpoint site at 0x%" PRIx64,
  m_address.GetOpcodeLoadAddress(&m_owner.GetTarget()));
  - return false;
  }
  - return true;
  + return IsResolved();
  }
  bool BreakpointLocation::SetBreakpointSite(BreakpointSiteSP &bp_site_sp) {
  