Fix test code to can be built on alpine

Signed-off-by: joseph <joseph@jc-lab.net>
diff --git a/ChangeLog.d/do-not-use-obsolete-header.txt b/ChangeLog.d/do-not-use-obsolete-header.txt
new file mode 100644
index 0000000..9a57ef1
--- /dev/null
+++ b/ChangeLog.d/do-not-use-obsolete-header.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Don't use the obsolete header path sys/fcntl.h in unit tests.
+     These header files cause compilation errors in musl.
+     Fixes #4969.
+