PPAPI: Remove clang plugins from ppapi/tests/clang

PPAPI: Remove clang plugins from ppapi/tests/clang

We don't use these anymore, and they have bitrotted and probably don't
even build with recent Clang. If we want them back, we can get them back
out of SVN/git.

R=teravest@chromium.org
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=272639

[teravest, 2014-05-23 16:19:24]

lgtm

[dmichael (off chromium), 2014-05-23 16:43:22]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-05-23 16:44:54]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dmichael@chromium.org/297963003/1

[commit-bot: I haz the power, 2014-05-23 18:24:19]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)

[commit-bot: I haz the power, 2014-05-23 20:22:29]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-05-23 20:22:29]

Try jobs failed on following builders:
  mac_chromium_rel on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/mac_chromium_rel/buil...)

[dmichael (off chromium), 2014-05-23 20:26:37]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-05-23 20:28:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dmichael@chromium.org/297963003/1

[commit-bot: I haz the power, 2014-05-23 23:48:41]

Change committed as 272639