Avoid potential divide by zero in BIO_dump_indent_cb()

Avoid potential divide by zero in BIO_dump_indent_cb()

Passing an indent value of 67 results in DUMP_WIDTH_LESS_IDENT returning a
value of zero, which is promptly used for division. Likewise, passing a
value larger than 67 results in a negative value being returned.

Prevent this by limiting indent to 64 (which matches OpenSSL's current
behaviour), as well as ensuring that dump_width is > 0.

Should fix oss-fuzz #52464 and #52467.

ok miod@ tb@