ARC: gcc - Fix SIZE_TYPE to be "unsigned int" instead of "long unsigned int"

This makes size_t to be "unsigned" ssize_t which makes happy compiler on data
type checks.

Fix is taken from current development branch of GCC for ARC and will be a
part of the next release of ARC tools, so at that point patch should be dropped.

https://github.com/foss-for-synopsys-dwc-arc-processors/gcc/commit/249f040299402647525c3f15b79d319fa7acddd3

Fixes http://autobuild.buildroot.net/results/405/405da9a945511329929b18740b983c51b8dcc43e



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