Replaced depricated %name-prefix= bison directive

frontends/ilang/parser.y

@@ -39,7 +39,7 @@ namespace ILANG_FRONTEND {
 using namespace ILANG_FRONTEND;
 %}
 
-%name-prefix="rtlil_frontend_ilang_yy"
+%name-prefix "rtlil_frontend_ilang_yy"
 
 %union {
 	char *string;

frontends/verilog/parser.y

@@ -84,7 +84,7 @@ static void free_attr(std::map<std::string, AstNode*> *al)
 
 %}
 
-%name-prefix="frontend_verilog_yy"
+%name-prefix "frontend_verilog_yy"
 
 %union {
 	std::string *string;