[Libguestfs] [PATCH nbdkit] tests: Invoke MALLOC_CHECK_ correctly and only for glibc

[Richard W.M. Jones]

... and also:
https://sourceware.org/bugzilla/show_bug.cgi?id=28256

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v