taglist: Fix broken empty set character in code

Previous one was not a valid ASCII empty set character.
'tig' and 'git log -p' couldn't represent it as expected.
18 jobs for fix-empty-set in 57 minutes and 35 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #326941
gst indent

00:00:32

passed #326940
manifest

00:00:41

 
  Build
passed #326942
build fedora x86_64

00:05:32

passed #326943
build nodebug fedora x86_64

00:05:14

 
  Test
passed #326944
check fedora

00:03:33

passed #326945
integration testsuites fedora

00:08:12

 
  Full Builds
passed #326947
build cerbero android universal

00:16:06

passed #326948
build cerbero cross win32

00:06:16

passed #326949
build cerbero cross win64

00:04:29

passed #326946
build cerbero fedora x86_64

00:07:56

 
  Full Tests
passed #326954
valgrind bad

00:11:34

passed #326951
valgrind base

00:11:46

passed #326950
valgrind core

00:15:57

passed #326955
valgrind ges

00:06:25

passed #326952
valgrind good

00:14:01

passed #326953
valgrind ugly

00:03:09

 
  Apps
passed #326956
android universal examples

00:07:43

 
  Deploy
passed #326957
documentation

00:03:21