Fix typo in comment

Author: Daniel Gustafsson <daniel@yesql.se>

src/backend/libpq/be-secure-openssl.c

@@ -610,7 +610,7 @@ be_tls_write(Port *port, void *ptr, size_t len, int *waitfor)
 		case SSL_ERROR_ZERO_RETURN:
 
 			/*
-			 * the SSL connnection was closed, leave it to the caller to
+			 * the SSL connection was closed, leave it to the caller to
 			 * ereport it
 			 */
 			errno = ECONNRESET;