IBM & Ricoh backends produce compiler warnings in Debian 10

Debian 10 gcc compiler generates the following warnings:

ibm.c: In function ‘attach’:
ibm.c:255:49: warning: argument to ‘sizeof’ in ‘strncat’ call is the same expression as the source; did you mean to use the size of the destination? [-Wsizeof-pointer-memaccess]
       strncat (str, (char *)ibuf.product, sizeof(ibuf.product));
                                                 ^
ibm.c:256:50: warning: argument to ‘sizeof’ in ‘strncat’ call is the same expression as the source; did you mean to use the size of the destination? [-Wsizeof-pointer-memaccess]
       strncat (str, (char *)ibuf.revision, sizeof(ibuf.revision));

The two backends IBM and RICOH share some of the same code and the warnings are identical.

These warnings should be suppressed with appropriate mitigations.

Referencing issue #120 (closed)