efi: fix build.

efi: fix build.

```
ninja -C build
ninja: Entering directory `build'
[29/101] Generating systemd_boot.so with a custom command.
FAILED: src/boot/efi/systemd_boot.so
/usr/bin/ld -o src/boot/efi/systemd_boot.so -T /usr/lib64/gnuefi/elf_x64_efi.lds -shared -Bsymbolic -nostdlib -znocombreloc -L /usr/lib64 /usr/lib64/gnuefi/crt0-efi-x64.o src/boot/efi/disk.c.o src/boot/efi/graphics.c.o src/boot/efi/measure.c.o src/boot/efi/pe.c.o src/boot/efi/util.c.o src/boot/efi/boot.c.o src/boot/efi/console.c.o src/boot/efi/crc32.c.o src/boot/efi/random-seed.c.o src/boot/efi/sha256.c.o src/boot/efi/shim.c.o -lefi -lgnuefi /usr/lib/gcc/x86_64-redhat-linux/10/libgcc.a
/usr/bin/ld: src/boot/efi/graphics.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/pe.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/util.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/boot.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/console.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/random-seed.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
/usr/bin/ld: src/boot/efi/shim.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: multiple definition of `loader_guid'; src/boot/efi/disk.c.o:/home/sus/tt/systemd/build/../src/boot/efi/util.h:58: first defined here
[31/101] Generating stub.c.o with a custom command.
ninja: build stopped: subcommand failed.
make: *** [Makefile:2: all] Error 1

```