busybox: use more featureful modprobe by default

The default version (modprobe-small) is missing important features,
and can also be _extremely_ slow (on purpose[1]).

The non-small modprobe implementation doesn't have all features
enabled by default, so by changing implementation we'd be risking
regression.  To mitigate that, I've ensured every feature checked for
in modprobe.c is enabled.  So unless there's functionality that's
_only_ in modprobe-small, we should be fine.

[1]: https://git.busybox.net/busybox/tree/modutils/Config.src?h=1_34_1#n8

pkgs/os-specific/linux/busybox/default.nix

@@ -81,6 +81,14 @@ stdenv.mkDerivation rec {
 
     CONFIG_LFS y
 
+    # More features for modprobe.
+    ${lib.optionalString (!enableMinimal) ''
+      CONFIG_FEATURE_MODPROBE_BLACKLIST y
+      CONFIG_FEATURE_MODUTILS_ALIAS y
+      CONFIG_FEATURE_MODUTILS_SYMBOLS y
+      CONFIG_MODPROBE_SMALL n
+    ''}
+
     ${lib.optionalString enableStatic ''
       CONFIG_STATIC y
     ''}