tests: add missing library

* tests/Makefile.am: Here.
9 jobs for er/tmp in 92 minutes and 36 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Build
passed alpine-gcc #93073

00:55:53

passed arch-clang #93074

00:51:26

passed arch-gcc-glibcxxdebug #93075

01:08:38

failed debian-gcc-snapshot #93072
allowed to fail

01:32:36

failed debian-stable-gcc #93070

01:02:25

failed debian-unstable-gcc-coverage #93071

01:19:31

passed mingw-shared #93076

00:09:22

passed mingw-static #93077

00:08:24

failed raspbian #93078
armv7

01:00:25

 
Name Stage Failure
failed
raspbian Build
No job log
failed
debian-gcc-snapshot Build
No job log
failed
debian-unstable-gcc-coverage Build
No job log
failed
debian-stable-gcc Build
No job log