[lld][Wasm] Wasm-ld emits invalid .debug_ranges entries for non-live symbols

When the debug info contains a relocation against a dead symbol, wasm-ld
may emit spurious range-list terminator entries (entries with Start==0
and End==0). This change fixes this by emitting the WasmRelocation
Addend as End value for a non-live symbol.

Reviewed by: sbc100, dblaikie

Differential Revision: https://reviews.llvm.org/D74781