ctypes: workaround unaligned pointer crash with clang 3.5

clang generates code which assumes that the PyCArgObject::value is 16 byte aligned but our current allocator only 8byte aligns
This made all code which used types crash on travis CI

from_cpython/Modules/_ctypes/ctypes.h

@@ -343,7 +343,8 @@ struct tagPyCArgObject {
 #ifdef HAVE_LONG_LONG
         PY_LONG_LONG q;
 #endif
-        long double D;
+        // Pyston change: disable this 16byte type because our allocator doesn't align allocs to 16byte.
+        // long double D;
         double d;
         float f;
         void *p;