loaders: JPG: Fix two bugs.
loaders: JPG: Fix two bugs.

* The fill_input_buffer() should use return from read not the buffer size

* The skip_input_data() should at least print warning if Seek failed

Signed-off-by: Cyril Hrubis <b1e90efd3b808b8e0bcf2a9a55fd8b9a779bfd81@ucw.cz>

gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim,gfxprim/gfxprim