fix format bug for elsestme and stmt def in .g4

src/ASTPrinter.cpp

@@ -155,7 +155,7 @@ std::any ASTPrinter::visitStmt(SysYParser::StmtContext *ctx){
       cout << getIndent() << "}" << endl;
     }
     if (ctx->stmt().size() > 1) {
-      cout << getIndent() << "else" << endl;
+      cout << getIndent() << "else";
       if(ctx->stmt(1)->blockStmt())ctx->stmt(1)->accept(this);
       else{
         cout << " {"<< endl;