bench: fix stutter bench compiler errors.

* NEWS: mention this fix.
* bench/stutter/stutter_bench.sh, bench/stutter/user.sh: Path to spot
  binaries would include an inexistant src directory.
* bench/stutter/stutter_invariance_formulas.cc: Add override qualifier
  to satisfy -Wsuggest-override.

NEWS

@@ -15,6 +15,9 @@ New in spot 2.3.2.dev (not yet released)
   - spot::twa_graph::purge_unreachable_states() was misbehaving on
     alternating automata.
 
+  - In bench/stutter/ the .cc files were not compiling due to warnings being
+    caught as errors.
+
 New in spot 2.3.2 (2017-03-15)
 
   Tools:

bench/stutter/stutter_bench.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 
-RANDLTL=../../src/bin/randltl
-LTLFILT=../../src/bin/ltlfilt
+RANDLTL=../../bin/randltl
+LTLFILT=../../bin/ltlfilt
 
 echo 'ltl-user-bench.csv:; ./user.sh' > run.mk
 

bench/stutter/stutter_invariance_formulas.cc

@@ -54,14 +54,14 @@ namespace
 
     int
     process_string(const std::string& input,
-                   const char* filename, int linenum)
+                   const char* filename, int linenum) override
     {
       formula = input;
       return job_processor::process_string(input, filename, linenum);
     }
 
     int
-    process_formula(spot::formula f, const char*, int)
+    process_formula(spot::formula f, const char*, int) override
     {
       spot::twa_graph_ptr a = trans.run(f);
       spot::twa_graph_ptr na = trans.run(spot::formula::Not(f));

bench/stutter/user.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
-RANDLTL=../../src/bin/randltl
-LTLFILT=../../src/bin/ltlfilt
-LTLDO=../../src/bin/ltldo
+RANDLTL=../../bin/randltl
+LTLFILT=../../bin/ltlfilt
+LTLDO=../../bin/ltldo
 
 set -e -x