ax25_to_tnc() is a little confused about tnc2buf length

[danak6jq]

Lines 148-153 of ax25.c are:

if (framelen > sizeof(tnc2buf) - 80) {
	/* Too much ! Too much! */
	return 0;
}

where tnc2buf is a function parameter char *tnc2buf. sizeof() has 'unsigned int' type, in a 32-bit binary, sizeof(char *) is 4U so this test re-writes
as:
if (framelen > 4U - 80U) {

which simplifies to:
if (framelen > 4294967224) {

Which I'll say is too much! too much! but sadly has nothing to do with the size of the supplied tnc2buf. Perhaps this test yearns to be:

    if (framelen > tnc2buflen) {

[danak6jq]

See issue #57