threadsnoop: increase PID field width and align to the right

for better readability.

Justifications:

https://ux.stackexchange.com/questions/13795/is-there-a-standard-to-left-justify-text-and-right-justify-numeric-values

wc -L /proc/sys/kernel/pid_max
7 /proc/sys/kernel/pid_max

CHANGELOG.md

@@ -60,6 +60,8 @@ and this project adheres to
   - [#2904](https://github.com/iovisor/bpftrace/pull/2904)
 - Use `strftime` instead of `elapsed` in `threadsnoop.bt`
   - [#2917](https://github.com/iovisor/bpftrace/pull/2917)
+- Increase PID field width and align to the right in `threadsnoop.bt`
+  - [#2927](https://github.com/iovisor/bpftrace/pull/2927)
 - Update runqlen.bt to remove `runnable_weight` field from cfs_rq struct.
   - [#2790](https://github.com/iovisor/bpftrace/pull/2790)
 - Update mdflush.bt to use blkdev.h instead of genhd.h for non-BTF builds.

tools/threadsnoop.bt

@@ -15,12 +15,12 @@
 
 BEGIN
 {
-	printf("%-15s %-6s %-16s %s\n", "TIME", "PID", "COMM", "FUNC");
+	printf("%-15s %7s %-16s %s\n", "TIME", "PID", "COMM", "FUNC");
 }
 
 uprobe:libpthread:pthread_create,
 uprobe:libc:pthread_create
 {
-	printf("%15s %-6d %-16s %s\n", strftime("%H:%M:%S.%f", nsecs), pid, comm,
+	printf("%15s %7d %-16s %s\n", strftime("%H:%M:%S.%f", nsecs), pid, comm,
 	    usym(arg2));
 }

tools/threadsnoop_example.txt

@@ -5,20 +5,20 @@ Tracing new threads via phtread_create():
 
 # ./threadsnoop.bt
 Attaching 2 probes...
-TIME            PID    COMM             FUNC
-10:20:31.938572 28549  dockerd          threadentry
-10:20:31.939213 28549  dockerd          threadentry
-10:20:31.939405 28549  dockerd          threadentry
-10:20:31.940642 28549  dockerd          threadentry
-10:20:31.949060 28549  dockerd          threadentry
-10:20:31.958319 28549  dockerd          threadentry
-10:20:31.939152 28549  dockerd          threadentry
-10:20:31.950978 28549  dockerd          threadentry
-10:20:32.013269 28579  docker-containe  0x562f30f2e710
-10:20:32.036764 28549  dockerd          threadentry
-10:20:32.083780 28579  docker-containe  0x562f30f2e710
-10:20:32.116738 629    systemd-journal  0x7fb7114955c0
-10:20:32.116844 629    systemd-journal  0x7fb7114955c0
+TIME                PID COMM             FUNC
+10:20:31.938572   28549 dockerd          threadentry
+10:20:31.939213   28549 dockerd          threadentry
+10:20:31.939405   28549 dockerd          threadentry
+10:20:31.940642   28549 dockerd          threadentry
+10:20:31.949060   28549 dockerd          threadentry
+10:20:31.958319   28549 dockerd          threadentry
+10:20:31.939152   28549 dockerd          threadentry
+10:20:31.950978   28549 dockerd          threadentry
+10:20:32.013269   28579 docker-containe  0x562f30f2e710
+10:20:32.036764   28549 dockerd          threadentry
+10:20:32.083780   28579 docker-containe  0x562f30f2e710
+10:20:32.116738     629 systemd-journal  0x7fb7114955c0
+10:20:32.116844     629 systemd-journal  0x7fb7114955c0
 [...]
 
 The output shows a dockerd process creating several threads with the start