x32: fix build regressions introduced by commit v4.7-96-g8435d67

x32: fix build regressions introduced by commit v4.7-96-g8435d67

* desc.c (printflock) [X32]: Add special handling required for
this architecture with sizeof(long) < sizeof(off_t).
* file.c [X32] (struct stat64): Add __attribute__((packed)).
[X32] (HAVE_STAT64): Define.
(printstat) [X32]: Redirect to printstat64.
(printstat64) [X32]: Use "struct stat" instead of "struct stat64".
[X32] (realprintstat64): Rename to printstat64_x32.
(sys_stat64, sys_fstat64) [X32]: Remove second definitions of these
functions.  Call printstat64_x32 instead of printstat64
* linux/x32/syscallent.h: Fix handlers for truncate and ftruncate.