Use emplace() for associative containers.

* HACKING: Adjust requirements.  g++4.8 is now OK
for all our targets.
* iface/dve2/dve2.cc, src/dstarparse/dstarparse.yy
src/dstarparse/nsa2tgba.cc, src/graph/ngraph.hh,
src/ltlast/atomic_prop.cc, src/ltlast/binop.cc, src/ltlast/bunop.cc,
src/ltlast/multop.cc, src/ltlast/unop.cc, src/ltlvisit/mark.cc,
src/ltlvisit/relabel.cc, src/taalgos/emptinessta.cc,
src/taalgos/tgba2ta.cc, src/tgba/tgbaexplicit.hh, src/tgba/tgbagraph.hh,
src/tgba/tgbasafracomplement.cc, src/tgba/tgbatba.cc,
src/tgbaalgos/cycles.cc, src/tgbaalgos/degen.cc,
src/tgbaalgos/dtbasat.cc, src/tgbaalgos/dtgbasat.cc,
src/tgbaalgos/emptiness.cc, src/tgbaalgos/gtec/gtec.cc,
src/tgbaalgos/ltl2tgba_fm.cc, src/tgbaalgos/magic.cc,
src/tgbaalgos/ndfs_result.hxx, src/tgbaalgos/reachiter.cc,
src/tgbaalgos/scc.cc, src/tgbaalgos/sccfilter.cc, src/tgbaalgos/se05.cc,
src/tgbaalgos/simulation.cc, src/tgbaalgos/tau03.cc,
src/tgbaalgos/tau03opt.cc, src/tgbaalgos/weight.cc: Use emplace()
instead of insert(make_pair(...)) or insert(...::value_type(...)).

src/tgbaalgos/magic.cc

@@ -484,7 +484,7 @@ namespace spot
       void add_new_state(const state* s, color c)
         {
           assert(h.find(s) == h.end());
-          h.insert(std::make_pair(s, c));
+          h.emplace(s, c);
         }
 
       void pop_notify(const state*) const