Fix Python 3.5 sizeof(PyGC_Head) for UBSan

...by again using 'long double' instead of 'double' to "force worst-case
alignment," just like Python 3.3 used to do.  This fixes -fsanitize=alignment
failures like

> workdir/UnpackedTarball/python3/Modules/_ctypes/_ctypes.c:2923:10: runtime error: member access within misaligned address 0x6110007af498 for type 'CDataObject' (aka 'struct tagCDataObject'), which requires 16 byte alignment
> 0x6110007af498: note: pointer points here
>  ff ff ff ff  01 00 00 00 00 00 00 00  98 98 17 00 90 61 00 00  00 00 00 00 00 00 00 00  00 00 00 00
>               ^
>  GenericPyCData_new workdir/UnpackedTarball/python3/Modules/_ctypes/_ctypes.c:2923:10
>  PyCFuncPtr_new workdir/UnpackedTarball/python3/Modules/_ctypes/_ctypes.c:3385:29
>  type_call workdir/UnpackedTarball/python3/Objects/typeobject.c:908:11
>  [...]

during PythonTest_dbaccess_python.

Change-Id: I8cc65823e1bc65807ec30c97a9099462e55c996d

external/python3/python-3.3.3-disable-obmalloc.patch.0

@@ -1,3 +1,14 @@
+--- Include/objimpl.h
++++ Include/objimpl.h
+@@ -250,7 +250,7 @@
+         union _gc_head *gc_prev;
+         Py_ssize_t gc_refs;
+     } gc;
+-    double dummy;  /* force worst-case alignment */
++    long double dummy;  /* force worst-case alignment */
+ } PyGC_Head;
+ 
+ extern PyGC_Head *_PyGC_generation0;
 --- Objects/obmalloc.c
 +++ Objects/obmalloc.c
 @@ -413,8 +413,8 @@