[ELF] Add --rosegment to complement --no-rosegment

This option can cancel --no-rosegment and it just seems right to have
a corresponding positive option for a --no-* negative option.

Anecdotally, gold had --rosegment but did not have --no-rosegment.
I added --no-rosegment (https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=9a6c68caa9543e09b064b7ac7c2b658f277bc19c) for binutils>=2.35