nitb/smpp: Add simple test runner for the issues found by daniel

Send the two strings that caused the read handling to misbehave.
Verify that we handle this correctly by still being able to issue
a VTY command. The CPU load issue could not be verified like this.
diff --git a/openbsc/tests/Makefile.am b/openbsc/tests/Makefile.am
index 31b2bb4..a29d9fb 100644
--- a/openbsc/tests/Makefile.am
+++ b/openbsc/tests/Makefile.am
@@ -31,7 +31,7 @@
                echo '  [$(PACKAGE_URL)])'; \
              } >'$(srcdir)/package.m4'
 
-EXTRA_DIST = testsuite.at $(srcdir)/package.m4 $(TESTSUITE) vty_test_runner.py ctrl_test_runner.py
+EXTRA_DIST = testsuite.at $(srcdir)/package.m4 $(TESTSUITE) vty_test_runner.py ctrl_test_runner.py smpp_test_runner.py
 TESTSUITE = $(srcdir)/testsuite
 DISTCLEANFILES = atconfig
 
@@ -41,6 +41,9 @@
 	osmotestconfig.py -p $(abs_top_srcdir) -w $(abs_top_builddir) -v
 	$(PYTHON) $(srcdir)/vty_test_runner.py -w $(abs_top_builddir) -v
 	$(PYTHON) $(srcdir)/ctrl_test_runner.py -w $(abs_top_builddir) -v
+if BUILD_SMPP
+	$(PYTHON) $(srcdir)/smpp_test_runner.py -w $(abs_top_builddir) -v
+endif
 	rm -f $(top_builddir)/hlr.sqlite3
 else
 python-tests: $(BUILT_SOURCES)