If a line did not end with '\r', then the final `\n' was replaced by
'\0' for parsing the current line. This `\0` was then mistakenly
considered as the end of the whole "ip route" output, so the remaining
lines were not parsed, causing "scrcpy --tcpip" to fail in some cases.
To fix the issue, read the final character of the current line before it
is (possibly) overwritten by '\0'.
The parser assumed that its input was a NUL-terminated string, but it
was not the case: it is just the raw output of "adb devices ip route".
In practice, it was harmless, since the output always ended with '\n'
(which was replaced by '\0' on truncation), but it was incorrect
nonetheless.
Always write a '\0' at the end of the buffer, and explicitly parse as a
NUL-terminated string. For that purpose, avoid the error-prone
sc_str_truncate() util function.
