tools/getdelays: add backward compatibility for taskstats version

tools/getdelays: add backward compatibility for taskstats version

Add version checks to print_delayacct() to handle differences in struct
taskstats across kernel versions.  Field availability depends on taskstats
version (t->version), corresponding to TASKSTATS_VERSION in kernel headers
(see include/uapi/linux/taskstats.h).

Version feature mapping:
- version >= 11  - supports COMPACT statistics
- version >= 13  - supports WPCOPY statistics
- version >= 14  - supports IRQ statistics
- version >= 16  - supports *_max and *_min delay statistics

This ensures the tool works correctly with both older and newer kernel
versions by conditionally printing fields based on the reported version.

eg.1
bash# grep -r "#define TASKSTATS_VERSION" /usr/include/linux/taskstats.h
"#define TASKSTATS_VERSION       10"
bash# ./getdelays -d -p 1
CPU                 count     real total  virtual total    delay total  delay average
                     7481     3786181709     3807098291       36393725          0.005ms
IO                  count    delay total  delay average
                      369     1116046035          3.025ms
SWAP                count    delay total  delay average
                        0              0          0.000ms
RECLAIM             count    delay total  delay average
                        0              0          0.000ms
THRASHING           count    delay total  delay average
                        0              0          0.000ms

eg.2
bash# grep -r "#define TASKSTATS_VERSION" /usr/include/linux/taskstats.h
"#define TASKSTATS_VERSION       14"
bash# ./getdelays -d -p 1
CPU                 count     real total  virtual total    delay total  delay average
                    68862   163474790046   174584722267    19962496806          0.290ms
IO                  count    delay total  delay average
                        0              0          0.000ms
SWAP                count    delay total  delay average
                        0              0          0.000ms
RECLAIM             count    delay total  delay average
                        0              0          0.000ms
THRASHING           count    delay total  delay average
                        0              0          0.000ms
COMPACT             count    delay total  delay average
                        0              0          0.000ms
WPCOPY              count    delay total  delay average
                        0              0          0.000ms
IRQ                 count    delay total  delay average
                        0              0          0.000ms

Link: https://lkml.kernel.org/r/20250731225326549CttJ7g9NfjTlaqBwl015T@zte.com.cn
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Wang Yaxin <wang.yaxin@zte.com.cn>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>