A few minor improvements to the script that builds the kernel version
tables:
* Improve the copy logic from the syscalls-table tool so that the
  the syscall tables are copied directly to target directory and not
  to a child directory
* Convert relative paths to absolute path.  The syscalls-table tool
  does not support relative paths
* Add the latest kernel version numbers to the built-in list.  (This
  isn't strictly required as the tool can handle arbitrary input from
  the user, but it's an easy update while we're already modifying the
  script.)

Signed-off-by: Tom Hromatka (Oracle) <tom.hromatka@gmail.com>

A few minor improvements to the script that updates the
syscalls.csv file:
* Remove file_getattr() and file_setattr() from the ignored
  syscalls list
* Properly initialize a new row (when a syscall is added) with
  PNR,SCMP_KV_UNDEF,... rather than PNR,PNR,...
* Add support for release candidate kernels
* Convert relative paths to absolute paths

Signed-off-by: Tom Hromatka (Oracle) <tom.hromatka@gmail.com>

Add documentation on how to update syscalls.csv. NOTE - since we haven't
fully converted syscalls.csv over to containing valid kernel version
numbers, I have intentionally set all kernel version fields to
SCMP_KV_UNDEF.  We'll update the kernel versions in pull request seccomp#457.

Here are the exact steps and results for updating syscalls.csv to
kernels v6.14 through v7.0-rc7

$ apt install libc6-dev-x32

$ git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
$ git clone https://github.com/hrw/syscalls-table.git
$ git clone git@github.com:<yourrepo>/libseccomp.git

$ cd libseccomp

$ vim include/seccomp-kvers.h
  --> add new syscall enumerations

$ time ./src/arch-build-kver-tables.py -d ../syscalls-table -k ../linux -V 6.14,6.15,6.16,6.17,6.18,6.19,7.0-rc7
Building version table for kernel 6.14
Building version table for kernel 6.15
Building version table for kernel 6.16
Building version table for kernel 6.17
Building version table for kernel 6.18
Building version table for kernel 6.19
Building version table for kernel 7.0-rc7

real    2m47.672s
user    1m22.094s
sys     1m23.954s

$ time ./src/arch-update-syscalls-csv.py -a -d ./ -k ../linux -c
src/syscalls.csv -V 6.14,6.15,6.16,6.17,6.18,6.19,7.0-rc7
Updating src/syscalls.csv version table for kernel 6.14
Updating src/syscalls.csv version table for kernel 6.15
Updating src/syscalls.csv version table for kernel 6.16
Updating src/syscalls.csv version table for kernel 6.17
Updating src/syscalls.csv version table for kernel 6.18
Updating src/syscalls.csv version table for kernel 6.19
Updating src/syscalls.csv version table for kernel 7.0-rc7

real    0m30.112s
user    0m20.716s
sys     0m9.547s

$ vim include-seccomp-syscalls.h
  --> add new syscall __SNR and __PNR entries as appropriate

$ ./src/arch-syscall-check
  --> Make changes as recommended by this script
  --> Re-run this script until there are no more changes to be made

$ cd src
$ ./arch-syscall-validate -c syscalls-prev.csv ../../linux/
$ git diff HEAD syscalls.csv
$ diff syscalls-prev.csv with syscalls.csv

Signed-off-by: Tom Hromatka (Oracle) <tom.hromatka@gmail.com>