Fix cases of variable shadowing in src/pdf/.

These were reviewed last year at http://review.skia.org/312480 but never
landed. Splitting into small chunks to land individually.

If we manage to fix all the existing cases of variable shadowing, we
could enable -Wshadow.

Change-Id: Ide60535395eddae3392ff37339fa32bdde612da6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/435878
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
3 files changed