write/elf: Allow disabling unique names for subsection

[bjorn3]

Currently object writes elf files with section names like .text.foo and .text.bar for the foo and bar sections. Elf allows naming both sections .text. This can save a lot of space on section name strings.

An api I could imagine would be to use .text as section name if the base section name is .text and the subsection name is empty. Currently this would result in the name .text. and panic if there are multiple subsections for the same section due to the same section name being inserted into a StringTable more than once.

[philipc]

Should this apply to COFF too? Mach-O will be fine because the name is ignored anyway.

[philipc]

panic if there are multiple subsections for the same section due to the same section name being inserted into a StringTable more than once.

Can you elaborate? I don't see where this would happen.