Fix parser/lexer generation with parallel make
Fix parser/lexer generation with parallel make

Fun fact: rules with multiple targets don't work properly with 'make
-j'. For example, a rule like

  a b: c
    touch a b

is equivalent to

  a: c
    touch a b

  b: c
    touch a b

so with 'make -j', the 'touch' command will be run twice. See
e.g. https://stackoverflow.com/questions/2973445/gnu-makefile-rule-generating-a-few-targets-from-a-single-source-file.

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