[lld] [lld-macho] Reduce memory usage of printing thunks in map file (PR #122785)

[Tom Stellard via llvm-commits]

tstellar wrote:

These are the CMake arguments I used to build LLVM if it helps: `cmake -G Ninja -B lld-build -S llvm/ -DCMAKE_BUILD_TYPE=Release -DLLVM_TARGETS_TO_BUILD="X86;AArch64" -DLLVM_ENABLE_PROJECTS=lld`

https://github.com/llvm/llvm-project/pull/122785