EvalState::resetFileCache: clear parse cache as well as eval cache
EvalState::resetFileCache: clear parse cache as well as eval cache

Fixes #2546.

(at least the basic reproduction I've been testing)

ehmry/nix,ehmry/nix,dtzWill/nix,rycee/nix,zimbatm/nix,NixOS/nix,vcunat/nix,zimbatm/nix,NixOS/nix,zimbatm/nix,ehmry/nix,dtzWill/nix,pikajude/nix,rycee/nix,pikajude/nix,vcunat/nix,rycee/nix,vcunat/nix,pikajude/nix,zimbatm/nix,ehmry/nix,ehmry/nix,ehmry/nix,vcunat/nix,rycee/nix,NixOS/nix,dtzWill/nix,dtzWill/nix,NixOS/nix,rycee/nix,NixOS/nix,dtzWill/nix