Adds HHVM runtime error code
Adds HHVM runtime error code

Ref: https://github.com/facebook/hhvm/blob/HHVM-3.8/hphp/runtime/base/runtime-error.h#L62
orchestral/lumen,crynobone/lumen-framework,Jaspur/lumen-framework,rakaaditya/lumen-framework,lasselehtinen/lumen-framework,rlacerda83/lumen-framework,callam/lumen-framework,Beanhunter/lumen-framework,cnanney/lumen-framework,scrubmx/lumen-framework,laravel/lumen-framework