value_to_string: use snprintf
value_to_string: use snprintf

Currently, value_to_string and debugger_value_to_string use an
error-prone calculation to avoid overflow. This was once adjusted
already, and one of the codepaths is still vulnerable. Put this in a
symfile:

    01:5678 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

and execute `p 1:$5679`. On Linux, the canary terminates the process.

LIJI32/SameBoy,LIJI32/SameBoy