our linkers (ld.bfd, ld.lld) by default uses ICF and gc-sections
1. gc-sections
This works only when -ffunction-sections is passed during compilation, and
its GCC specific.
Makes no sense to enable LD --gc-sections when our default %optflags does
not emit -ffunction-sections -fdata-sections
2. ICF
Same as above, without -ffunction-sections -fdata-sections in optflags it
make no sense
3. Unsafe ?
We are the only ones who enabled ICF and gc-section in gold and LLD. I
really wonder if these uncommon options gives any advantage these days.