swipe-tracker: Fix a leak in …_confirm_swipe()

The swipe tracker takes ownership of the heap-allocated snap points in
hdy_swipe_tracker_confirm_swipe(), but if any of the preconditions fail
the function would return without freeing that memory. This uses an auto
cleanup function to handle these many cases automatically.
11 jobs for swipe-leak-fix in 20 minutes and 40 seconds
Status Job ID Name Coverage
  Build
passed #246304
librem5
api-visibility

00:02:19

passed #246306
librem5
build-debian-clang

00:03:27

passed #246305
librem5
build-debian-gcc

00:02:34

passed #246307
librem5
build-fedora-gcc

00:03:10

 
  Test+Docs
passed #246308
librem5
build-gtkdoc

00:02:24

passed #246309
librem5
unit-test

00:02:21

43.6%
 
  Package
passed #246310
librem5
package-debian-buster

00:02:45

passed #246311
librem5:arm64
package-debian-buster:arm64

00:06:37

failed #246312
flatpak allowed to fail
package-flatpak

00:00:52

 
  Test Package
passed #246313
librem5
autopkgtest-debian-buster-package

00:02:30

passed #246314
librem5
lintian-debian-buster-package

00:00:57

 
Name Stage Failure
failed
package-flatpak Package
Committing stage finish to cache
Exporting sm.puri.Handy.Demo to repo
error: Writing content object: min-free-space-percent '3%' would be exceeded, at least 4.1?kB requested
Export failed: Child process exited with code 1
Uploading artifacts...
_build/meson-logs/meson-log.txt: found 1 matching files
WARNING: sm.puri.Handy.Demo-dev.flatpak: no matching files
Uploading artifacts to coordinator... ok
id=246312 responseStatus=201 Created token=3nhYWK6j
ERROR: Job failed: exit code 1