Close all the log fds before aborting

We should close the sigsafe_log_fds before abort(), so that we are less likely to lose log lines in the fd buffers.

Here are the abort() users:

• tor_abort_()
• crash_handler()
• format_number_sigsafe()
• raw_assert()
• raw_assert_unreached_msg()
• trunnel_abort()

We could:

• define a raw_abort() function that closes the fds
• use it instead of abort()
• #define trunnel_abort() as raw_abort()
• update our C linter to require raw_abort() instead of abort()