tests: add getrusage.test

* tests/getrusage.c: New file.
* tests/getrusage.test: New test.
* tests/.gitignore: Add getrusage.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(TESTS): Add getrusage.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index a37c052..3cded8d 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -37,6 +37,7 @@
 getdents
 getdents64
 getrandom
+getrusage
 getxxid
 inet-cmsg
 ioctl