boot1.efi: use += to append to LDFLAGS
commit57e094b7d5d447ddc3eb9a860063ffbe8f473016
authoremaste <emaste@FreeBSD.org>
Tue, 8 Mar 2016 17:45:56 +0000 (8 17:45 +0000)
committeremaste <emaste@FreeBSD.org>
Tue, 8 Mar 2016 17:45:56 +0000 (8 17:45 +0000)
tree91fa22b1a95d1bc87e850daeb66f8e27d831c290
parentd29ea6698cc7869406874fd2bafa12b223243fa1
boot1.efi: use += to append to LDFLAGS

This is for consistency with loader.efi's Makefile and simplifies some
out-of-tree experimentation.
sys/boot/efi/boot1/Makefile