rename kexec-tools-static

it doesn't build natively on x86-64 and I don't suppose we need it to
anyway

modules/kexecboot.nix

@@ -20,7 +20,7 @@ in {
         ln -s ${o.kernel} kernel
         ln -s ${o.manifest} manifest
         ln -s ${o.boot-sh} boot.sh
-        ln -s ${pkgs.kexec-tools}/bin/kexec ./kexec
+        ln -s ${pkgs.kexec-tools-static}/bin/kexec ./kexec
         ln -s ${o.dtb} dtb
      '';
 

overlay.nix

@@ -16,7 +16,7 @@ in
 extraPkgs // {
   strace = prev.strace.override { libunwind = null; };
 
-  kexec-tools = prev.kexec-tools.overrideAttrs(o: {
+  kexec-tools-static = prev.kexec-tools.overrideAttrs(o: {
     # For kexecboot we copy kexec into a ramdisk on the system being
     # upgraded from. This is more likely to work if kexec is
     # statically linked so doesn't have dependencies on store paths that