BUILD/MEDIUM: cfgparse: get rid of sprintf()

A few occurrences of sprintf() were causing harmless warnings on OpenBSD :

src/cfgparse.o(.text+0x259e): In function `cfg_parse_global':
src/cfgparse.c:1044: warning: sprintf() is often misused, please use snprintf()

These ones were easy to get rid of, so better do it.
1 file changed