add timestamp to diagnostic log entries

[vladak]

When using the diagnostic log to track down problems with an IdP, I found that it would benefit from having time stamps written to the log, somewhere around here:

mod_auth_mellon/auth_mellon_diagnostics.c

Lines 705 to 706 in b1e30ff

	apr_file_puts("---------------------------------- New Request"
	" ---------------------------------\n", diag_cfg->fd);

and here

mod_auth_mellon/auth_mellon_diagnostics.c

Line 767 in b1e30ff

apr_file_puts("\n=== Response ===\n", diag_cfg->fd);

[3eka]

+1

[thijskh]

A pull request would be very welcome!