Properly translate touch screen events into mouse drag ones

* doc/lispref/commands.texi (Drag Events): Correct misleading
example form and reword subsequent elaboration.

* lisp/touch-screen.el (touch-screen-handle-point-up)
<mouse-drag>: Set posns representing drag start and terminus to
mouse position lists, in lieu of pairs between windows and posns
employed previously.
10 jobs for master in 203 minutes and 58 seconds (queued for 6 seconds)
Status Job ID Name Coverage
  Build Images
passed #74947
build-image-inotify

01:49:05

 
  Normal
failed #74948
test-all-inotify

00:51:28

 
  Platform Images
passed #74949
build-image-eglot

01:41:11

failed #74951
build-image-gnustep

00:34:00

passed #74950
build-image-tree-sitter

01:48:35

 
  Platforms
passed #74952
test-eglot

00:03:53

skipped #74954
test-gnustep
passed #74953
test-tree-sitter

00:01:40

 
  Native Comp Images
passed #74955
build-native-comp-speed2

02:28:43

 
  Native Comp
failed #74956
test-native-comp-speed2

00:55:10

 
Name Stage Failure
failed
test-native-comp-speed2 Native Comp
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
$ find ${test_name} -type d -depth -exec rmdir {} + 2>/dev/null
Uploading artifacts...
test-native-comp-speed2-ad2bb3e9/: found 531 matching files
Uploading artifacts to coordinator... ok
id=74956 responseStatus=201 Created token=jsnEKxaQ
Uploading artifacts...
test-native-comp-speed2-ad2bb3e9/junit-test-report.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=74956 responseStatus=201 Created token=jsnEKxaQ
ERROR: Job failed: exit code 2
failed
test-all-inotify Normal
Uploading artifacts for failed job
Uploading artifacts...
test-all-inotify-ad2bb3e9/: found 531 matching files and directories

Uploading artifacts as "archive" to coordinator... 201 Created
id=74948 responseStatus=201 Created token=frWLdCx_
Uploading artifacts...
test-all-inotify-ad2bb3e9/junit-test-report.xml: found 1 matching files and directories

Uploading artifacts as "junit" to coordinator... 201 Created
id=74948 responseStatus=201 Created token=frWLdCx_
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 2

failed
build-image-gnustep Platform Images
 > [emacs-gnustep 6/6] RUN make bootstrap:
------
executor failed running [/bin/sh -c make bootstrap]: exit code: 2
Running after script...
$ test -n "$(docker ps -aq -f name=${test_name})" && docker cp ${test_name}:checkout/test ${test_name}
$ test -n "$(docker ps -aq -f name=${test_name})" && docker rm ${test_name}
$ find ${test_name} ! \( -name "*.log" -o -name ${EMACS_TEST_JUNIT_REPORT} \) -type f -delete
find: build-image-gnustep-ad2bb3e9: No such file or directory
ERROR: Job failed: exit code 1