Re-enable frame pointers for optimized code

[JohanEngelen]

See: https://issues.dlang.org/show_bug.cgi?id=24439 https://news.ycombinator.com/item?id=39731824 https://www.brendangregg.com/blog/2024-03-17/the-return-of-the-frame-pointers.html and https://github.com/ldc-developers/ldc/issues/2222

Code change will be simply to adjust this: https://github.com/ldc-developers/ldc/blob/3eb31901b3d253b3f23b8599111d930994696ef7/gen/functions.cpp#L507-L508

[kinke]

So should we do this? But keep them disabled for 32-bit x86 only?