mpd-mpc: new package

[Thomas:
 - Changed hash file to use SHA256
 - Remove libiconv handling, since the iconv detection in mpc is
   broken: if it's not available in the C library, it expects to find
   iconv() in libintl (from gettext). But it's actually libiconv that
   provides iconv() for non-locale capable uClibc toolchains. But
   since anyway the package builds fine without iconv() support and
   properly detects when it's available, don't bother with this.]

Signed-off-by: Thierry Bultel <tbultel@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>