Pass -Wno-format-truncation when this is supported by GCC so silence
warnings like this:
conf.c: In function ‘Read_Config’:
conf.c:985:60: warning: ‘snprintf’ output may be truncated before
the last format character [-Wformat-truncation=]
985 | snprintf(file, sizeof(file), "%s/%s",
| ^
conf.c:985:25: note: ‘snprintf’ output 2 or more bytes (assuming 257)
into a destination of size 256
985 | snprintf(file, sizeof(file), "%s/%s",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
986 | Conf_IncludeDir, entry->d_name);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The warning is correct, but this is basically why we use snprintf() in
the first place.