rendercopy: Remove rendercopy.c

Move scratch_buf_write_to_png() to its only user, gem_render_copy.c.
This makes the cairo dependencies easier to handle from the Android
perspective, but if there is a good reason why this file exists I can
try to handle it differently.

Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/rendercopy.h

@@ -89,6 +89,4 @@ void gen2_render_copyfunc(struct intel_batchbuffer *batch,
 			  unsigned width, unsigned height,
 			  struct scratch_buf *dst, unsigned dst_x, unsigned dst_y);
 
-void scratch_buf_write_to_png(struct scratch_buf *buf, const char *filename);
-
 #endif /* RENDERCOPY_H */