tests/testsuite.at: ensure empty stderr for the bitvec_test

The address sanitizer may print errors and warnings to stderr, and
this was actually the case for bitvec_test before [1]:

  bitvec.c:492:24: runtime error: shift exponent 64 is too large
                                  for 64-bit type 'long unsigned int'

Change-Id: Ia82b92eddb18dc596881abcef2f098dc7385538b
Related: [1] I4deeabba7ebb720cdbe7c85b37bc011d05bdfa65
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 975b51e..92c4e39 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -36,7 +36,7 @@
 AT_SETUP([bitvec])
 AT_KEYWORDS([bitvec])
 cat $abs_srcdir/bitvec/bitvec_test.ok > expout
-AT_CHECK([$abs_top_builddir/tests/bitvec/bitvec_test], [0], [expout], [ignore])
+AT_CHECK([$abs_top_builddir/tests/bitvec/bitvec_test], [0], [expout])
 AT_CLEANUP
 
 AT_SETUP([bitcomp])