Set $NIX_DEBUG_INFO_DIRS when environment.enableDebugInfo is enabled

This allows it to co-exist with other debug info directories, such as
the one used by dwarffs
(https://github.com/edolstra/dwarffs/blob/master/module.nix).

Changed files
+4 -3
nixos
modules
+4 -3
nixos/modules/config/debug-info.nix
···
};
-
config = {
+
config = mkIf config.environment.enableDebugInfo {
# FIXME: currently disabled because /lib is already in
# environment.pathsToLink, and we can't have both.
#environment.pathsToLink = [ "/lib/debug/.build-id" ];
-
environment.extraOutputsToInstall =
-
optional config.environment.enableDebugInfo "debug";
+
environment.extraOutputsToInstall = [ "debug" ];
+
+
environment.variables.NIX_DEBUG_INFO_DIRS = [ "/run/current-system/sw/lib/debug" ];
};