[llvm] Use MapVector to fix lld thinLTO bep issue. (PR #117551)

[via llvm-commits]

llvmssh wrote:

@pcc，@vitalybuka Hi, can you help review my code?  thank you.
Fix the issue:
During the generation of ModuleSymbolTable, the unordered DenseMap data structure is traversed during the collection of Asm symbols. As a result, the sequence of symbols in the symbol table is inconsistent after the ThinLTO lld link. As a result, binary random inconsistency occurs. Made a simple data structure modification.

https://github.com/llvm/llvm-project/pull/117551