tests: add read-write.test

* tests/read-write.c: New file.
* tests/read-write.test: New test.
* tests/.gitignore: Add read-write.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add read-write.test.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 12afd49..0f4a329 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -148,6 +148,7 @@
 	preadv-pwritev \
 	pselect6 \
 	pwritev \
+	read-write \
 	readdir \
 	readlink \
 	readlinkat \
@@ -334,6 +335,7 @@
 	preadv-pwritev.test \
 	pselect6.test \
 	pwritev.test \
+	read-write.test \
 	readdir.test \
 	readlink.test \
 	readlinkat.test \