Bug fixes

• Don't loading system certs from Keychain on iOS (#1546)
• Initialize sockaddr_un to fix valgrind uninitialised byte message. (#1547
• #1547)
• Using set_content_provider with length of 0 makes it infinitely loop #1545
• How to check if server is running successfully in another thread? #1548
• Fix leaked handle in create_socket (#1554)