[PATCH][Gold] Fix for incremental copy test

[Miguel Saldivar <saldivarcher at gmail dot com>]

This is a possible solution for fixing the incremental_copy_test
within the gold testsuite.
The issue stems from how gcc-9 handles .rodata sections, more can be
seen here: https://sourceware.org/bugzilla/show_bug.cgi?id=24123.

I figured there was two possible ways to solve this problem, either
handle this on the first run or on the second run.
The first run, compiling with the `--incremental-full`, a solution
would be to set any `.rodata` prefix flag to `A`
instead of `AM`; `AM` is the flag that is outputted in the first run for.

Or the other method when running: `--incremental-update`, or the
second run would be to expect an `AM` rather than a `A`.

But for this case I chose the former rather than the latter, because
the ELF file should have an `.rodata`
section with a flag of `A`, and this ensures that.

Attachment: incremental-copy-test-fix.txt
Description: Text document