local_bitvector_analysist::merge: use bitwise or

This avoids a jump. On a goto function of 160822 instructions, the total
time required by local bitvector analysis decreases from 72 seconds to
65 seconds (averaged over three runs, the difference between the slowest
and longest run is below 0.2 seconds).

Author: tautschnig

src/analyses/local_bitvector_analysis.cpp

@@ -45,10 +45,7 @@ bool local_bitvector_analysist::merge(points_tot &a, points_tot &b)
     std::max(a.size(), b.size());
 
   for(std::size_t i=0; i<max_index; i++)
-  {
-    if(a[i].merge(b[i]))
-      result=true;
-  }
+    result |= a[i].merge(b[i]);
 
   return result;
 }