package/upmpdcli: Fix build with uclibc on SH4

Add missing header file <cstdio> to the uclibc patch to fix build with
target SH4.

Fixes:
  http://autobuild.buildroot.net/results/e5be8fe46a30f0b417fe5fc19a27c480d885791e/
  http://autobuild.buildroot.net/results/a3453afddff4fc03681f7fbdff3ccab9706eb189/



[Thomas: further improve the patch by adding a missing <errno.h>
include.]

Signed-off-by: Jörg Krause <jkrause@posteo.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>