simple_sprintf() -> snprintf() and fix format specifier / datatype for time_t

[michaelortmann]

Found by: michaelortmann
Patch by: michaelortmann
Fixes:

One-line summary:
simple_sprintf() -> snprintf() and fix format specifier / datatype for time_t

Additional description (if needed):
See also:

eggdrop/src/botmsg.c

Lines 138 to 141 in 541e8ac

	// TODO: this should probably not be used eggdrop core anymore
	// and only stay for 3rd party module compatibility
	// Reason: No sane compiler error checking possible, hardcoded 1024 limit
	int simple_sprintf (char *buf, const char *format, ...)

eggdrops simple_sprintf() brings a %D specifier for converting int to base64. Those are harder to migrate to snprintf(). But all others should be migrated over time. One benefit is indeed that the compiler will be able to do more checks.

Test cases demonstrating functionality (if applicable):