bin: diagnose more write errors

* tests/core/full.test: New file.
* tests/Makefile.am: Add it.
* bin/autfilt.cc, bin/common_aoutput.cc, bin/common_aoutput.hh,
bin/common_file.cc, bin/common_file.hh, bin/genltl.cc, bin/ltlcross.cc,
bin/ltlfilt.cc, bin/ltlgrind.cc, bin/randltl.cc: Add diagnostics.
* NEWS: Mention the fix.

bin/ltlcross.cc

@@ -1396,6 +1396,7 @@ print_stats_csv(const char* filename)
           vstats[r][t].to_csv(out, !opt_omit);
           out << '\n';
         }
+  outf.close(filename);
 }
 
 static void
@@ -1442,6 +1443,7 @@ print_stats_json(const char* filename)
           out << " ]";
         }
   out << "\n  ]\n}\n";
+  outf.close(filename);
 }
 
 int