[lld] [LLD][COFF] Use EC symbol table for output DEF file on ARM64X (PR #125531)

[Jacek Caban via llvm-commits]

cjacek wrote:

Since this is a MinGW extension, we define its meaning. Other command-line arguments apply either to the EC symbol table or both, so for consistency, we should use the EC symbol table.

For the input DEF file, a new command-line option, `-defarm64native`, specifies the native symbol table instead. We could introduce a similar option for the output DEF file, but I’m not sure it’s necessary. My suggestion is to skip it for now and add it later if there’s demand.

https://github.com/llvm/llvm-project/pull/125531