setup hello_gpu.h/c to not directly depend on header defs from psyq

code/duffle/gp.h

@@ -74,6 +74,7 @@ typedef def_enum(U32, gp_Commands) {
 #define gp_SetArea_BottomRight (gcmd_SetDrawArea_BotRight << gcmd_offset)
 
 typedef def_struct(RGB8) { BYTE r; BYTE g; BYTE b; };
+#define rgba8(r, g, b) (RGB8){ r, g, b }
 
 typedef BYTE gp_Pixel16[1];
 typedef BYTE gp_Pixel24[3];
@@ -85,6 +86,7 @@ typedef BYTE gp_Pixel24[3];
 
 typedef def_struct(gp_Vec2) { U16 y; U16 x; };
 
+
 #if 1
 void gp_screen_init(void) __asm__("gp_screen_init_asm");
 #else

code/duffle/math.h

@@ -23,3 +23,5 @@ typedef def_struct(Range_2S32) { Vec_2S32 p0; Vec_2S32 p1; };
 
 typedef def_struct(Rect_S16) { S16 x; S16 y; S16 width; S16 height; };
 typedef def_struct(Rect_S32) { S32 x; S32 y; S32 width; S32 height; };
+
+#define vec_2s16(x, y) (Vec_2S16){ x, y }