Issue description

efivar.pc uses a prefix of /usr/include

Steps to reproduce

nix-shell '<nixpkgs>' -A efibootmgr --command 'pkg-config --cflags efivar'

It doesn't have to be efibootmgr: any package that uses efivar will do.

I'm trying to package a utility (mokutil) that uses efivar via pkg-config and it can't find <efivar.h> because pkg-config --cflags efivar returns -I/usr/include/efivar.

efibootmgr builds because its derivation doesn't rely on using pkg-config. It uses NIX_CFLAGS_COMPILE = "-I${efivar}/include/efivar";.

I've added this attribute to my derivation for mokutil and it now builds, but it shouldn't be necessary to add this.

Technical details

• system: "x86_64-linux"
• host os: Linux 4.9.80, NixOS, 17.09.3008.c831224528c (Hummingbird)
• multi-user?: yes
• sandbox: no
• version: nix-env (Nix) 1.11.16
• channels(user): ""
• channels(root): "nixos-17.09.3008.c831224528c, unstable-18.03pre126508.8ecadc12502"
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs