fix: usr: Add chroot check to meson.build

The meson build procedure was not checking for the existence of
the chroot function.  This has been fixed.

Closes #5519

Merge branch '5519-add-chroot-check-to-meson-build' into 'main'

See merge request isc-projects/bind9!10973

meson.build

@@ -515,6 +515,7 @@ foreach fn, header : {
     'sched_yield': '#include <sched.h>',
 
     # Misc.
+    'chroot': '#include <unistd.h>',
     'clock_gettime': '#include <time.h>',
     'sysctlbyname': '#include <sys/sysctl.h>',
 }