We're currently building GCC with the system binutils, which, at the
moment, is whatever version is available on the CentOS 6 build
environments. With the imminent switch to Debian 7, that will be a
different version.
It turns out the GCC configure script does enable some features
depending on the binutils it's built with. For the most notable
differences it makes when going from Centos 6 to Debian, it enables
.init_array/.fini_array depending on the binutils version, and enables
the use of CFI advances depending on gas and objdump respectively
supporting and displaying DW_CFA_advance_loc.
But we're already building a fixed version of binutils (which happens to
be more recent than the one in both CentOS 6 and Debian 7), and we're
using that version when using GCC to build, so we can just as much use
the version we built to build GCC.
In order to avoid any changes to the resulting builds, we explicitly
turn off .init_array/.fini_array (which currently happens implicitly
when building on CentOS 6). This will ensure that there is not other
change to the builds due to this binutils version bump
(.init_array/.fini_array being enabled shifts everything in the
binaries, so it makes the whole diff full of noise)
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