Merge to XFA: Make DEPS use relative paths to fix recipe

Merge to XFA: Make DEPS use relative paths to fix recipe

Context: DEPS was originally added to pdfium to allow its recipe to
automatically check out its dependencies. The recipe used absolute
paths, and so the checkout directory's name ('pdfium') had to be
prefixed to the directory checkout of every dependency, as gclient in
the recipe worked one level above the pdfium checkout itself.

After change fe4537269fc7133320a5131638757f2ffa6bd854, the recipe no
longer worked. To fix this, I'm making DEPS use relative paths.

BUG=375773
TBR=tsepez@chromium.org

Review URL: https://codereview.chromium.org/724113003

(cherry picked from commit 39c6b4c50bb06336c2b592a407efa862ff6ed8ae)

Committed: https://pdfium.googlesource.com/pdfium/+/e4bf83403b6791dda2afe3827a124df4f8c62237

[Lei Zhang, 2015-10-22 00:11:00]

TBR, clean merge. Without this, gclient sync does not work right on XFA.

[Lei Zhang, 2015-10-22 00:11:08]

Committed patchset #1 (id:1) manually as
e4bf83403b6791dda2afe3827a124df4f8c62237 (presubmit successful).

[Tom Sepez, 2015-10-22 00:12:46]

Any of the hashes need updating? LGTM otherwise.

[Lei Zhang, 2015-10-22 00:17:10]

On 2015/10/22 00:12:46, Tom Sepez wrote:
> Any of the hashes need updating? LGTM otherwise.

Ya, v8 is out of date. I'll remember to merge the v8 rolls starting next week.