madplay: fix build on noMMU platforms

madplay: fix build on noMMU platforms

A recent change in uClibc-ng removed the MADV_* definitions for
madvise(), but kept the madvise() function itself. This defeats the
logic used in madplay: it checks if madvise() is available, and if it
is, uses it and assumes the MADV_* definitions exist.

This inconsistency has been reported to upstream uClibc-ng, but in the
mean time, we can simply tell madplay to not use madvise(), which is
anyway useless on noMMU platforms.

Fixes:

  http://autobuild.buildroot.net/results/3291554ea013e5f4a8f3447e10e664dffa8b131b/

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