dead code: add static const qualifier to constant sets

sapfor/experts/Sapfor_2017/_src/Transformations/dead_code.cpp

@@ -52,7 +52,7 @@ static void updateUseDefForInstruction(SAPFOR::BasicBlock* block, SAPFOR::Instru
 
     if (!useful)
     {
-        set<SAPFOR::CFG_OP> always_useful =
+        static const set<SAPFOR::CFG_OP> always_useful =
         {
             SAPFOR::CFG_OP::POINTER_ASS,
             SAPFOR::CFG_OP::STORE,
@@ -456,7 +456,7 @@ void removeDeadCode(SgStatement* func,
     }
 
     // remove dead statements
-    set<int> removable =
+    static const set<int> removable =
     {
         ASSIGN_STAT,
         PROC_STAT,
@@ -464,7 +464,7 @@ void removeDeadCode(SgStatement* func,
         READ_STAT
     };
 
-    set<int> skip =
+    static const set<int> skip =
     {
         PROG_HEDR,
         PROC_HEDR,