Add olivec_copy() to the header

olive.c

@@ -301,6 +301,7 @@ OLIVECDEF void olivec_line(Olivec_Canvas oc, int x1, int y1, int x2, int y2, uin
 OLIVECDEF void olivec_triangle(Olivec_Canvas oc, int x1, int y1, int x2, int y2, int x3, int y3, uint32_t color);
 OLIVECDEF void olivec_triangle3(Olivec_Canvas oc, int x1, int y1, int x2, int y2, int x3, int y3, uint32_t c1, uint32_t c2, uint32_t c3);
 OLIVECDEF void olivec_text(Olivec_Canvas oc, const char *text, int x, int y, Olivec_Font font, size_t size, uint32_t color);
+OLIVECDEF void olivec_copy(Olivec_Canvas src, Olivec_Canvas dst, int x, int y, int w, int h);
 
 // The point of this function is to produce two ranges x1..x2 and y1..y2 that are guaranteed to be safe to iterate over the canvas of size pixels_width by pixels_height without any boundary checks.
 //