C API: Add SK_API, also documentation of an example.

include/c/sk_path.h

Index: include/c/sk_path.h
diff --git a/include/c/sk_path.h b/include/c/sk_path.h
index 801e1480f93129aa3e629a3ba10e25b2f1afa759..d13a11219fcec01185449e25a8489f0215bdad24 100644
--- a/include/c/sk_path.h
+++ b/include/c/sk_path.h
@@ -20,25 +20,28 @@ typedef enum {
     CCW_SK_PATH_DIRECTION,
 } sk_path_direction_t;
 
-sk_path_t* sk_path_new();
-void sk_path_delete(sk_path_t*);
-
-void sk_path_move_to(sk_path_t*, float x, float y);
-void sk_path_line_to(sk_path_t*, float x, float y);
-void sk_path_quad_to(sk_path_t*, float x0, float y0, float x1, float y1);
-void sk_path_conic_to(sk_path_t*, float x0, float y0, float x1, float y1, float w);
-void sk_path_cubic_to(sk_path_t*, float x0, float y0, float x1, float y1, float x2, float y2);
-void sk_path_close(sk_path_t*);
-
-void sk_path_add_rect(sk_path_t*, const sk_rect_t*, sk_path_direction_t);
-void sk_path_add_oval(sk_path_t*, const sk_rect_t*, sk_path_direction_t);
+SK_API sk_path_t* sk_path_new();
+SK_API void sk_path_delete(sk_path_t*);
+
+SK_API void sk_path_move_to(sk_path_t*, float x, float y);
+SK_API void sk_path_line_to(sk_path_t*, float x, float y);
+SK_API void sk_path_quad_to(sk_path_t*, float x0, float y0, float x1, float y1);
+SK_API void sk_path_conic_to(sk_path_t*, float x0, float y0, float x1, float y1, float w);
+SK_API void sk_path_cubic_to(sk_path_t*,
+                             float x0, float y0,
+                             float x1, float y1,
+                             float x2, float y2);
+SK_API void sk_path_close(sk_path_t*);
+
+SK_API void sk_path_add_rect(sk_path_t*, const sk_rect_t*, sk_path_direction_t);
+SK_API void sk_path_add_oval(sk_path_t*, const sk_rect_t*, sk_path_direction_t);
 
 /**
  *  If the path is empty, return false and set the rect parameter to [0, 0, 0, 0].
  *  else return true and set the rect parameter to the bounds of the control-points
  *  of the path.
  */
-bool sk_path_get_bounds(const sk_path_t*, sk_rect_t*);
+SK_API bool sk_path_get_bounds(const sk_path_t*, sk_rect_t*);
 
 SK_C_PLUS_PLUS_END_GUARD