As of today ARCompact (AKA "ARCv1 ISA") processors (mostly those are ARC770)
are not officially supported by upstream glibc as it adds quite some burden
on release ans support of yet another "architecture" port.
But given on ABI and ISA front ARCompact is very close to ARCv2 we may
easily retrofit its support off-the-tree, which we do here.
Also given amount of changes we need to apply there's a hope it will be easy
and straight-forward to apply the same to later versions of glibc.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>