m4 is required to build the test SELinux module:
```
[ 31.321789] sh[483]: /bin/sh: line 1: m4: command not found
[ 31.882668] sh[488]: Compiling targeted systemd_test module
[ 32.120862] sh[492]: /bin/sh: line 1: m4: command not found
[ 32.159897] sh[458]: make: *** [/usr/share/selinux/devel/include/Makefile:156: tmp/systemd_test.mod] Error 127
```