[Decompilation] [th01] Line loop blitting

Wait, so if this is only used for the rotating white squares around
Mima, that must mean that the white star in the YuugenMagan fight got a
completely redundant reimplementation…

Part of P0121, funded by Yanga.

th01/hardware/graph.h

@@ -78,6 +78,12 @@ void graph_r_line_unput(
 void graph_r_box(
 	screen_x_t left, vram_y_t top, screen_x_t right, vram_y_t bottom, int col
 );
+
+// Draws lines in the given [col] from each of the given X/Y points to the
+// next one, and then back from the last point to the first one.
+void graph_r_lineloop_put(
+	const screen_x_t x[], const vram_y_t y[], int point_count, int col
+);
 /// -----------------------
 
 /// Text

th01/main/shape.cpp

@@ -211,3 +211,16 @@ void shape_invincibility_put_with_mask_from_B_plane(
 	}
 	grcg_off();
 }
+
+// Why is this here?
+void graph_r_lineloop_put(
+	const screen_x_t x[], const vram_y_t y[], int point_count, int col
+)
+{
+	int i = 0;
+	while((point_count - 1) > i) {
+		graph_r_line(x[i], y[i], x[i + 1], y[i + 1], col);
+		i++;
+	}
+	graph_r_line(x[i], y[i], x[0], y[0], col);
+}