toolchain: bump ARC tools to arc-2016.03 release

toolchain: bump ARC tools to arc-2016.03 release

This change switches ARC tools to the most recent arc-2016.03
version.

ARC GNU tools of version arc-2016.03 bring some quite significant
changes like:
 * Binutils v2.26+ (upstream commit id 202ac19 with additional ARC
 * patches)
 * GCC v4.8.5
 * GDB 7.10

More about changes, improvements and fixes could be found here:
https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/releases/tag/arc-2016.03

Note in this change we're adding sha512 checksums for
both binutils and gcc tarballs fetched from GitHub.

Build and run-tested in nSIM for both ARC700 and ARC HS38.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>