I experienced that error too. it seems your virtual machine has low amount of rams. But you can fix it. See below
free
dd if=/dev/zero of=/var/swap.img bs=1024k count=1000
mkswap /var/swap.img
swapon /var/swap.img
free
make -f makefile.unix USE_UPNP=- all
thanks @Bgn91
I did what you said before, but when i run ./mutualcoind i see this error:
MutualCoin: Unable to bind to 0.0.0.0:25731 on this computer. MutualCoin is probably already running.
MutualCoin: Failed to listen on any port. Use -listen=0 if you want this.