This fixes the following warnings from clang 14:
usr.sbin/kbdmap/kbdmap.c:241:16: error: 'sscanf' may overflow; destination buffer in argument 5 has size 20, but the corresponding specifier may require size 21 [-Werror,-Wfortify-source]
&a, &b, buf);
^
usr.sbin/kbdmap/kbdmap.c:615:8: error: 'sscanf' may overflow; destination buffer in argument 3 has size 64, but the corresponding specifier may require size 65 [-Werror,-Wfortify-source]
keym, lng, desc);
^
usr.sbin/kbdmap/kbdmap.c:615:14: error: 'sscanf' may overflow; destination buffer in argument 4 has size 64, but the corresponding specifier may require size 65 [-Werror,-Wfortify-source]
keym, lng, desc);
^
usr.sbin/kbdmap/kbdmap.c:615:19: error: 'sscanf' may overflow; destination buffer in argument 5 has size 256, but the corresponding specifier may require size 257 [-Werror,-Wfortify-source]
keym, lng, desc);
^
In each case, the buffer being sscanf'd into is one byte too small.
MFC after: 3 days
