package/mpd: fetch upstream patch to fix GCC 6 issue

package/mpd: fetch upstream patch to fix GCC 6 issue

Fetch a patch from upstream to fix a build issue with GCC 6:

'''
In file included from /home/joerg/Development/git/buildroot/output/host/usr/arm-buildroot-linux-gnueabi/include/c++/6.1.0/bits/stl_algo.h:59:0,
                 from /home/joerg/Development/git/buildroot/output/host/usr/arm-buildroot-linux-gnueabi/include/c++/6.1.0/algorithm:62,
                 from ./src/queue/IdTable.hxx:25,
                 from ./src/queue/Queue.hxx:24,
                 from src/queue/Playlist.hxx:23,
                 from src/Partition.hxx:23,
                 from src/Instance.cxx:22:
/home/joerg/Development/git/buildroot/output/host/usr/arm-buildroot-linux-gnueabi/include/c++/6.1.0/cstdlib:75:25: fatal error: stdlib.h: No such file or directory
 #include_next <stdlib.h>
'''

Bug report: https://bugs.musicpd.org/view.php?id=4524
Fetch from: aa5d05eaa4d482aa8f8df954335d0aba151eeff9

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>