configure: enable Lua if found and continue without if not
configure: enable Lua if found and continue without if not

Search for Lua if no --enable-lua/--disable-lua specified but continue
without if not found.

If --enable-lua is specified and Lua is not found then return error.

If --disable-lua is specified, then don't search for Lua.

Signed-off-by: Natanael Copa <d6dfbe96822fc6f407d114112670f8d1571509f1@alpinelinux.org>
Acked-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

glensc/lxc,armcc/lxc,szaszg/lxc,lisongmin/lxc,rldleblanc/lxc,Ponce/lxc,efiop/lxc,hallyn/lxc,virajs/lxc,bostjan/lxc,LynxChaus/lxc,regit/lxc,jirislaby/lxc,Pelagicore/lxc,lisongmin/lxc,bmoar/lxc,hfuCN/lxc,raspberrypython/lxc,hkjolhede/lxc,federicobriata/lxc,jirislaby/lxc,akshaykarle/lxc,ecarrara/lxc,ojkastl/lxc_Patches,Ponce/lxc,ysbnim/lxc,ioops/lxc,Pelagicore/lxc,tych0/lxc,raspberrypython/lxc,federicobriata/lxc,sapun/lxc,ksperis/lxc,armcc/lxc,rowhit/lxc,fwilson42/lxc,hfuCN/lxc,szaszg/lxc,terceiro/lxc,yubo/lxc,caglar10ur/lxc,bmoar/lxc,rowhit/lxc,christiaan/lxc,virajs/lxc,Distrotech/lxc,major/lxc,DarknessBeforeDawn/lxc,rldleblanc/lxc,ss1h2a3tw/lxc,ksperis/lxc,glensc/lxc,tych0/lxc,regit/lxc,lisongmin/lxc,ioops/lxc,cjwatson/lxc,ojkastl/lxc_Patches,lazy404/lxc,bmoar/lxc,QingweiPeterLan/cs188-lxc,lazy404/lxc,caglar10ur/lxc,raspberrypython/lxc,efiop/lxc,terceiro/lxc,Pelagicore/lxc,akshaykarle/lxc,christiaan/lxc,fwilson42/lxc,hallyn/lxc,major/lxc,cjwatson/lxc,sapun/lxc,thmo/lxc,GreatFruitOmsk/lxc,ysbnim/lxc,GreatFruitOmsk/lxc,weizhenwei/lxc,ss1h2a3tw/lxc,cjwatson/lxc,glensc/lxc,JohnPeacockMessageSystems/lxc,aeris/lxc,QingweiPeterLan/cs188-lxc,hallyn/lxc,DarknessBeforeDawn/lxc,armcc/lxc,bostjan/lxc,szaszg/lxc,JohnPeacockMessageSystems/lxc,sapun/lxc,hfuCN/lxc,codebauss/lxc,ojkastl/lxc_Patches,LynxChaus/lxc,aeris/lxc,ioops/lxc,rowhit/lxc,yubo/lxc,bostjan/lxc,lazy404/lxc,QingweiPeterLan/cs188-lxc,thmo/lxc,LynxChaus/lxc,aeris/lxc,caglar10ur/lxc,Ponce/lxc,Distrotech/lxc,ecarrara/lxc,yubo/lxc,ojkastl/lxc_Patches,federicobriata/lxc,christiaan/lxc,rldleblanc/lxc,hkjolhede/lxc,terceiro/lxc,virajs/lxc,major/lxc,tych0/lxc,ksperis/lxc,thmo/lxc,ss1h2a3tw/lxc,efiop/lxc,DarknessBeforeDawn/lxc,JohnPeacockMessageSystems/lxc,regit/lxc,akshaykarle/lxc,codebauss/lxc,jirislaby/lxc,codebauss/lxc,hkjolhede/lxc,ysbnim/lxc,GreatFruitOmsk/lxc,weizhenwei/lxc,Distrotech/lxc,fwilson42/lxc,ecarrara/lxc,weizhenwei/lxc