gstlal: add check for bad disconts from resampler

- the audioresampler in gstreamer 1.x no longer produces bad discont flags.
  we can remove all use of lal_nofakedisconts element, but before we do
  this patch adds a test to make sure the bug doesn't reappear

gstlal/tests/Makefile.am

@@ -13,6 +13,7 @@ EXTRA_DIST = \
 	lal_reblock_test_01.sh \
 	matrixmixer_test_01.py \
 	resample_test_01.py \
+	resample_test_02.sh \
 	segmentsrc_test_01.py \
 	statevector_test_01.py \
 	sumsquares_test_01.py \
@@ -23,7 +24,7 @@ EXTRA_DIST = \
 	peak_test_01.py \
 	drop_test_01.py
 
-TESTS = cachesrc_test_01.sh firbank_test_01.py gate_test_01.py lal_reblock_test_01.sh matrixmixer_test_01.py resample_test_01.py segmentsrc_test_01.py statevector_test_01.py sumsquares_test_01.py togglecomplex_test_01.py whiten_test_01.py peak_test_01.py drop_test_01.py
+TESTS = cachesrc_test_01.sh firbank_test_01.py gate_test_01.py lal_reblock_test_01.sh matrixmixer_test_01.py resample_test_01.py resample_test_02.sh segmentsrc_test_01.py statevector_test_01.py sumsquares_test_01.py togglecomplex_test_01.py whiten_test_01.py peak_test_01.py drop_test_01.py
 
 pkgpython_PYTHON = \
 	cmp_nxydumps.py

gstlal/tests/resample_test_02.sh

+#!/bin/sh
+
+# check for bad discont flags in output of audioresample by generating a
+# stream with 1 sample per buffer, and then downsampling to a lower sample
+# rate so that some input buffers produce no output buffers.  the correct
+# behaviour is for it to produce buffers with no data, but old versions
+# produced no buffer followed by a buffer marked as a discont (due to
+# unavoidable behaviour in the GstBaseTransform class from which it is
+# derived).
+
+run_test() {
+	gst-launch-1.0 \
+		audiotestsrc wave=0 samplesperbuffer=1 num-buffers=1024 \
+		! audio/x-raw,rate=512,format=F64LE,channels=1 \
+		! audioresample \
+		! audio/x-raw,rate=128 \
+		! lal_checktimestamps \
+		! fakesink
+}
+
+! run_test 2>&1 | grep -q "lal_checktimestamps"