Changing jerry_ref_unused_variables signature to take values by const reference.
Changing jerry_ref_unused_variables signature to take values by const reference.

yichoi/jerryscript,robertsipka/jerryscript,tilmannOSG/jerryscript,gabrielschulhof/jerryscript,LeeHayun/jerryscript,martijnthe/jerryscript,dbatyai/jerryscript,bsdelf/jerryscript,akosthekiss/jerryscript,jerryscript-project/jerryscript,jerryscript-project/jerryscript,bsdelf/jerryscript,LaszloLango/jerryscript,LeeHayun/jerryscript,glistening/jerryscript,zherczeg/jerryscript,jack60504/jerryscript,dbatyai/jerryscript,LaszloLango/jerryscript,jack60504/jerryscript,robertsipka/jerryscript,grgustaf/jerryscript,grgustaf/jerryscript,LeeHayun/jerryscript,martijnthe/jerryscript,martijnthe/jerryscript,glistening/jerryscript,martijnthe/jerryscript,grgustaf/jerryscript,dbatyai/jerryscript,glistening/jerryscript,akosthekiss/jerryscript,loki04/jerryscript,grgustaf/jerryscript,jack60504/jerryscript,bzsolt/jerryscript,bsdelf/jerryscript,robertsipka/jerryscript,tilmannOSG/jerryscript,jerryscript-project/jerryscript,bzsolt/jerryscript,jerryscript-project/jerryscript,slaff/jerryscript,LaszloLango/jerryscript,dbatyai/jerryscript,robertsipka/jerryscript,glistening/jerryscript,jack60504/jerryscript,martijnthe/jerryscript,glistening/jerryscript,bzsolt/jerryscript,gabrielschulhof/jerryscript,bsdelf/jerryscript,zherczeg/jerryscript,slaff/jerryscript,tilmannOSG/jerryscript,robertsipka/jerryscript,bzsolt/jerryscript,jack60504/jerryscript,loki04/jerryscript,yichoi/jerryscript,glistening/jerryscript,zherczeg/jerryscript,LaszloLango/jerryscript,slaff/jerryscript,loki04/jerryscript,martijnthe/jerryscript,loki04/jerryscript,grgustaf/jerryscript,yichoi/jerryscript,zherczeg/jerryscript,akosthekiss/jerryscript,robertsipka/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,bsdelf/jerryscript,slaff/jerryscript,grgustaf/jerryscript,bsdelf/jerryscript,jerryscript-project/jerryscript,bzsolt/jerryscript,loki04/jerryscript,yichoi/jerryscript,tilmannOSG/jerryscript,zherczeg/jerryscript,gabrielschulhof/jerryscript,LeeHayun/jerryscript,jack60504/jerryscript,LeeHayun/jerryscript,gabrielschulhof/jerryscript,akosthekiss/jerryscript,gabrielschulhof/jerryscript,LaszloLango/jerryscript,yichoi/jerryscript,loki04/jerryscript,slaff/jerryscript,tilmannOSG/jerryscript