tests: add getcwd.test

* tests/getcwd.c: New file.
* tests/getcwd.test: New test.
* tests/.gitignore: Add getcwd.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(TESTS): Add getcwd.test.
diff --git a/tests/.gitignore b/tests/.gitignore
index 449af18..d1fb6d4 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -42,6 +42,7 @@
 fstatat64
 ftruncate
 ftruncate64
+getcwd
 getdents
 getdents64
 getrandom