Fix checkdeps breakage introduced by r11723
Fix checkdeps breakage introduced by r11723

Add DEPS entry so that pnacl/support/ can #include header files from
itself.

This checkdeps failure wasn't caught by the PNaCl toolchain trybots
because they don't run checkdeps.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3484
TEST=run "python tools/checkdeps/checkdeps.py"

Review URL: https://codereview.chromium.org/18612010

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11724 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client