Remove unused deep_copy function callback

Author: Smit-create

src/libasr/codegen/c_utils.h

@@ -136,7 +136,6 @@ namespace CPPUtils {
     }
 } // namespace CPPUtils
 
-typedef std::string (*DeepCopyFunction)(std::string, std::string, ASR::ttype_t*);
 
 class CCPPDSUtils {
     private:
@@ -151,7 +150,6 @@ class CCPPDSUtils {
         std::string func_decls;
 
         SymbolTable* global_scope;
-        DeepCopyFunction deepcopy_function;
 
     public:
 
@@ -160,10 +158,6 @@ class CCPPDSUtils {
             func_decls.clear();
         }
 
-        void set_deepcopy_function(DeepCopyFunction func) {
-            deepcopy_function = func;
-        }
-
         void set_indentation(int indendation_level_, int indendation_space_) {
             indentation_level = indendation_level_;
             indentation_spaces = indendation_space_;