Fix sources needed for lld.

[bdrewery]

Summary

lld always needs these DWARF sources, as well as other default and extra
tools. XDL seems to be the best fit list.

Remove MK_LLD_IS_LD check from SRCS_MIW which is now reduced to just a
few files for llvm-objdump.

Sponsored by: Dell EMC

Test Plan

local builds
I removed all of these from the lld build and added one at a time until it passed to determine this list.