[llvm-branch-commits] [NFC][ELF] Don't duplicate DynamicReloc constructor (PR #150811)

[Jessica Clarke via llvm-branch-commits]

https://github.com/jrtc27 created https://github.com/llvm/llvm-project/pull/150811

This second constructor is just a shorthand for an AddendOnly relocation
against dummySym with R_ADDEND, so write it as such.