[llvm-objdump] Support --symbolize-operands when there is a single...

[llvm-objdump] Support --symbolize-operands when there is a single SHT_LLVM_BB_ADDR_MAP section for all text sections

When linking, using `-Wl,-z,keep-text-section-prefix` results in multiple text sections while all `SHT_LLVM_BB_ADDR_MAP` sections are linked into a single one.
In such case, we should not read the corresponding section for each text section, and instead read all `SHT_LLVM_BB_ADDR_MAP` sections before disassembly.

Reviewed By: jhenderson, MaskRay

Differential Revision: https://reviews.llvm.org/D129924