linux bootstrap for musl: kludgery

pkgs/stdenv/linux/bootstrap-tools-musl/default.nix

···
   # Needed by the GCC wrapper.
   langC = true;
   langCC = true;
-  isGNU = false;
+  isGNU = true;
 }

pkgs/stdenv/linux/default.nix

···
 { lib
 , localSystem, crossSystem, config, overlays
 
-, bootstrapFiles ? { # switch
+, bootstrapFiles ? if localSystem.libc == "musl" then import ./bootstrap-files/musl64.nix
+else { # switch
     "i686-linux" = import ./bootstrap-files/i686.nix;
     "x86_64-linux" = import ./bootstrap-files/x86_64.nix;
     "armv5tel-linux" = import ./bootstrap-files/armv5tel.nix;
···
 
 
   # Download and unpack the bootstrap tools (coreutils, GCC, Glibc, ...).
-  bootstrapTools = import ./bootstrap-tools { inherit system bootstrapFiles; };
+  bootstrapTools = import (if localSystem.libc == "musl" then ./bootstrap-tools-musl else ./bootstrap-tools) { inherit system bootstrapFiles; };
 
 
   # This function builds the various standard environments used during
···
         buildCommand = ''
           mkdir -p $out
           ln -s ${bootstrapTools}/lib $out/lib
+        '' + lib.optionalString (localSystem.libc == "glibc") ''
           ln -s ${bootstrapTools}/include-glibc $out/include
+        '' + lib.optionalString (localSystem.libc == "musl") ''
+          ln -s ${bootstrapTools}/include-libc $out/include
         '';
       };
       gcc-unwrapped = bootstrapTools;