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

[Vitaly Buka via llvm-commits]

vitalybuka wrote:

> Thanks for your reply. When a compiler of the same version builds the same project twice, the generated binary files are different, which is reflected in the inconsistent sequence in the symbol table. For example: 295: 000000000000 0 FUNC GLOBAL DEFAULT UND [__lxstat at GLIBC_2.X](mailto:__lxstat at GLIBC_2.X) 295: 000000000000 0 FUNC GLOBAL DEFAULT UND [__libc_start_main at GLIBC_2.X](mailto:__libc_start_main at GLIBC_2.X)

Sorry, out of curiosity are there definition of "bep"? 

Regardless of definition, can we please just call it "nondeterminism" in title and description? I guess that's how we usually call it in LLVM.



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