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/configure.ac b/configure.ac
index 7d8e6dd..dc43509 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3,6 +3,7 @@
 	[openbsc-devel@lists.openbsc.org])
 
 AM_INIT_AUTOMAKE([dist-bzip2])
+AC_CONFIG_TESTDIR(tests)
 
 dnl kernel style compile messages
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
@@ -138,6 +139,10 @@
 	AC_DEFINE([PANIC_INFLOOP],[1],[Use infinite loop on panic rather than fprintf/abort])
 fi
 
+
+AC_CONFIG_FILES(tests/osmo-test, chmod +x tests/osmo-test)
+dnl AC_CONFIG_FILES(tests/atlocal)
+
 AC_OUTPUT(
 	libosmocore.pc
 	libosmocodec.pc