build: show the logo in named mode

When running `zig build -Dn=n`, ensure that the logo is printed.

Update the tests.

Closes #214

build.zig

@@ -153,8 +153,11 @@ pub fn build(b: *Build) !void {
             b.fmt("Check the solution of {s}", .{ex.main_file}),
         );
         b.default_step = zigling_step;
+        zigling_step.dependOn(&header_step.step);
 
         const verify_step = ZiglingStep.create(b, ex, work_path);
+        verify_step.step.dependOn(&header_step.step);
+
         zigling_step.dependOn(&verify_step.step);
 
         return;

test/tests.zig

@@ -151,6 +151,16 @@ const CheckNamedStep = struct {
         defer stderr_file.close();
 
         const stderr = stderr_file.reader();
+        {
+            // Skip the logo.
+            const nlines = mem.count(u8, root.logo, "\n");
+            var buf: [80]u8 = undefined;
+
+            var lineno: usize = 0;
+            while (lineno < nlines) : (lineno += 1) {
+                _ = try readLine(stderr, &buf);
+            }
+        }
         try check_output(step, ex, stderr);
     }
 };