[LLDB] Handle DIE with DW_AT_low_pc and empty ranges

The case comes out of how BOLT handles transformation of
DW_AT_low_pc/DW_AT_high_pc into DW_AT_low_pc/DW_AT_high_pc
with latter being 0.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D127889