various fixes

* comptime expression is a block expression as it should be
 * fix var args when number of args passed is 0
 * implement const value equality for structs
 * fix indent when rendering container decl AST
 * IR: prevent duplicate generation of code when it is partially
   compile-time evaluated
 * implement compile time struct field pointer evaluation
 * fix compile time evaluation of slicing

src/ast_render.cpp

@@ -600,6 +600,7 @@ static void render_node_extra(AstRender *ar, AstNode *node, bool grouped) {
                 }
 
                 ar->indent -= ar->indent_size;
+                print_indent(ar);
                 fprintf(ar->f, "}");
                 break;
             }