tests: add a test for basic network syscalls

* tests/.gitignore: Add net-accept-connect, *.o and *.log.*.
* tests/Makefile.am (AM_CFLAGS): New variable.
(check_PROGRAMS): Add net-accept-connect.
(TESTS): Add net.
* tests/net-accept-connect.c: New file.
* tests/net: New file.
diff --git a/tests/.gitignore b/tests/.gitignore
index 7e563b8..947455d 100644
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -1,2 +1,5 @@
+net-accept-connect
 *.log
+*.log.*
+*.o
 *.trs