By Anthony Boadle BRASILIA (Reuters) -President Jair Bolsonaro invited the diplomatic corps on Monday to hear his charges that Brazil’s election system was open to fraud ahead of October elections in which he is trailing in a bid for a second term. “The system is completely vulnerable,” he told some 40 diplomats invited to his residence in an unprecedented briefing three months before a general election. Bolsonaro gave no evidence of fraud, but said a hacker got inside the electronic voting system during the election he won in 2018, an incident that police concluded had not compromised the res…