build-sys: build gummiboot executable only if HAVE_BLKID
build-sys: build gummiboot executable only if HAVE_BLKID

src/setup/setup.c depends on blkid library. so build gummiboot
binary only if blkid library is available.

todorez/tummiboot,miguelinux/gummiboot2systemd-boot,todorez/tummiboot,aaronp24/gummiboot,aaronp24/gummiboot,trilean/gummiboot,freedesktop-unofficial-mirror/gummiboot,todorez/gummiboot-multiboot2,trilean/gummiboot,todorez/gummiboot-multiboot2,freedesktop-unofficial-mirror/gummiboot,miguelinux/gummiboot2systemd-boot