Always install llvm-objdump as objdump

Instead of providing no /usr/bin/objdump when LLVM_BINUTILS is false.

PR: 267854 [exp-run]
Reviewed by: dim
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D37445

(cherry picked from commit 86edb11e7491e657e6c75ef6814867021665c377)