check-qdict: Fix possible crash

This warning is reported by cppcheck:

check-qdict.c:270: warning: scanf without field width limits can crash with huge input data

Fix it by limiting the field widths to 127 (both key and value take
127 characters + a terminating '\0' byte).

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
