Backport !1522 “meson: Fix gnulib printf checks” to glib-2-64

Philip Withnallrequested to merge
pwithnall/glib:backport-1522-meson-printf-checks-glib-2-64 into glib-2-64

Some typos, and accidental usage of the strings 'true' / 'false' instead of the booleans true / false.

Trivial backport of !1522 (merged) to glib-2-64.

Merge request reports