XFA: clang-format all pdfium code.

No behavior change.

Generated by:
  find . -name '*.cpp' -o -name '*.h' | \
  grep -E -v 'third_party|thirdparties|lpng_v163|tiff_v403' | \
  xargs ../../buildtools/mac/clang-format -i
Then manually merged https://codereview.chromium.org/1269223002/

See thread "tabs vs spaces" on pdfium@googlegroups.com for discussion.

BUG=none
1110 files changed