tests: Use GNU autotest to execute our tests and compare textual output

The output of make check is looking like this now:

Regression tests.

  1: bits                                            ok
  2: msgfile                                         ok
  3: sms                                             ok
  4: smscb                                           ok
  5: timer                                           FAILED (testsuite.at:38)
  6: ussd                                            FAILED (testsuite.at:44)
diff --git a/tests/testsuite.at b/tests/testsuite.at
new file mode 100644
index 0000000..df5a5e8
--- /dev/null
+++ b/tests/testsuite.at
@@ -0,0 +1,45 @@
+AT_INIT
+AT_TESTED(osmo-test)
+
+AT_BANNER([Regression tests.])
+
+
+# todo.. create one macro for it
+AT_SETUP([bits])
+AT_KEYWORDS([bits])
+cat $abs_srcdir/bits/bitrev_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/bits/bitrev_test], [], [expout])
+AT_CLEANUP
+
+if ENABLE_MSGFILE
+AT_SETUP([msgfile])
+AT_KEYWORDS([msgfile])
+cp $abs_srcdir/msgfile/msgconfig.cfg .
+cat $abs_srcdir/msgfile/msgfile_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/msgfile/msgfile_test], [], [expout])
+AT_CLEANUP
+endif
+
+AT_SETUP([sms])
+AT_KEYWORDS([sms])
+cat $abs_srcdir/sms/sms_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/sms/sms_test], [], [expout])
+AT_CLEANUP
+
+AT_SETUP([smscb])
+AT_KEYWORDS([smscb])
+cat $abs_srcdir/smscb/smscb_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/smscb/smscb_test], [], [expout])
+AT_CLEANUP
+
+AT_SETUP([timer])
+AT_KEYWORDS([timer])
+cat $abs_srcdir/timer/timer_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/timer/timer_test], [], [expout])
+AT_CLEANUP
+
+AT_SETUP([ussd])
+AT_KEYWORDS([ussd])
+cat $abs_srcdir/ussd/ussd_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/ussd/ussd_test], [], [expout])
+AT_CLEANUP