Rename pdfium/bug_511_jbig_null_crash.pdf.0.png.

Fix presubmit test to ignore deleted files.

Change-Id: Ida20c9629803f963d6a92cedf4abbd701caeb11c
Reviewed-on: https://pdfium-review.googlesource.com/3630
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>