Use ppapi_sources.gypi for nacl trusted build.scons like the untrusted nacl.scons does.

Use ppapi_sources.gypi for nacl trusted build.scons like the untrusted nacl.scons does (mirroring nacl.scons changes in http://codereview.chromium.org/8727029/)

R=noelallen@chromium.org,bradnelson@chromium.org
BUG= none
TEST= ppNaClPlugin builds in nacl via scons.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=112822

[jvoung - send to chromium..., 2011-12-02 22:55:18]

ptal

[bradn, 2011-12-02 23:54:29]

lgtm