ppl011: Fix building with Clang 3.4+.

* Since [1], Clang doesn't allow flexible array member of class with
  non-default destructor or virtual member function. This breaks the
  compiler check for ppl.
* Improve the compiler test to catch this case.
* Use a slightly different patch to avoid running autoreconf.

[1] http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20140106/096974.html