x32: fix struct dirent decoding

x32: fix struct dirent decoding

* kernel_types.h: New file.
* Makefile.am (strace_SOURCES): Add it.
* configure.ac (AC_CHECK_TYPES): Check for __kernel_long_t
and __kernel_ulong_t in <asm/posix_types.h>.
* dirent.c: Stop including <dirent.h>.
(kernel_dirent): Remove.
Include "kernel_types.h".
(print_old_dirent, SYS_FUNC(getdents)): Print variables
of kernel_ulong_t type using %Lu format.
* syscall.c (kernel_long_t, kernel_ulong_t): Remove.
Include "kernel_types.h".
* tests/getdents.c (kernel_dirent): Remove.
Include "kernel_types.h".
(print_dirent): Print variables of kernel_ulong_t type using %Lu format.