tools: Fix a buffer overflow involving a file name in pngfix

Reported-by: Guoxiang Niu (@niugx), EaglEye Team
Reported-by: Riccardo Mori <patacca@autistici.org>
Reviewed-by: John Bowler <jbowler@acm.org>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
1 file changed