Add support for preventing OOM kill on certain VMs.

ansible/roles/bhyve/files/bhyverc.bash

@@ -38,6 +38,7 @@ fi
 : ${VNC_WIDTH:="1920"}
 : ${VNC_HEIGHT:="1080"}
 : ${BIND9P:=""}
+: ${PREVENT_OOM:="NO"}
 : "${CD:=}"
 
 : ${SHUTDOWN_TIMEOUT:="600"} # 10 minutes
@@ -278,6 +279,10 @@ function start_body {
     local mac_address
     mac_address=$(calculate_mac_address "$name")
 
+    if [ "$PREVENT_OOM" = "YES" ]; then
+        protect -d -i -p "$$"
+    fi
+
     local additional_args=()
 
     if [ "$NETWORK" = "NAT" ]; then