More corpus tests PNG updates

This CL updates a couple of Linux and a bunch of Mac PNGs for FT
revision c56d8851ea987023cc73981a70d261b3f6427545. It also updates
two Linux expectations.

Bug: chromium:738919
Change-Id: I9c0223922333d583aa39042404e13beb05624742
Reviewed-on: https://pdfium-review.googlesource.com/7470
Reviewed-by: dsinclair <dsinclair@chromium.org>