meson: Fix gnulib printf checks

Some typos, and accidental usage of the strings `'true'` / `'false'`
instead of the booleans `true` / `false`.
15 jobs for meson-fix-gnulib-printf-checks in 51 minutes and 13 seconds (queued for 1 second)
Status Job ID Name Coverage
  Style Check
passed #758468
check-todos

00:01:04

passed #758467
style-check-diff

00:01:05

 
  Build
passed #758473
cross-android_api21_arm64

00:03:19

passed #758474
cross-android_api28_arm64

00:01:37

passed #758475
cross-mingw64

00:04:44

passed #758470
debian-stable-x86_64

00:10:01

passed #758469
fedora-x86_64

00:17:46

passed #758523
G_DISABLE_ASSERT

00:03:48

passed #758471
installed-tests

00:11:46

passed #758476
win32-ps
msys2-mingw32

00:10:24

passed #758477
win32-ps
vs2017-x64

00:08:39

failed #758472
G_DISABLE_ASSERT

00:04:43

 
  Coverage
passed #758478
coverage

00:02:23

78.2%
 
  Analysis
passed #758480
scan-build

00:17:40

failed #758479
allowed to fail
valgrind

00:26:09

 
Name Stage Failure
failed
valgrind Analysis
Uploading artifacts...
_build/config.h: found 1 matching files

_build/glib/glibconfig.h: found 1 matching files

_build/meson-logs: found 7 matching files

Uploading artifacts to coordinator... ok
id=758479 responseStatus=201 Created token=CDksxUz8
Uploading artifacts...
_build/valgrind-report.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=758479 responseStatus=201 Created token=CDksxUz8
ERROR: Job failed: exit code 1