Dockerfile: Remove high UID/GID

When running Docker with user namespace remapping, the UID/GID of the
files must be in the 0 - 65535 range. One toolchain's tar file included
files outside of that range and thus I could not run the image on my
GitLab runners. This patch fixes that and the U-Boot CI completes just
fine in my environment.
Signed-off-by: Harm Berntsen <harm.berntsen@nedap.com>
CC: Tom Rini <trini@konsulko.com>

Dockerfile

@@ -29,7 +29,7 @@ RUN wget -O - https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_
 
 # Manually install other toolchains
 RUN wget -O - https://github.com/foss-xtensa/toolchain/releases/download/2018.02/x86_64-2018.02-xtensa-dc233c-elf.tar.gz | tar -C /opt -xz
-RUN wget -O - https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/releases/download/arc-2019.09-release/arc_gnu_2019.09_prebuilt_uclibc_le_archs_linux_install.tar.gz | tar -C /opt -xz
+RUN wget -O - https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/releases/download/arc-2019.09-release/arc_gnu_2019.09_prebuilt_uclibc_le_archs_linux_install.tar.gz | tar --no-same-owner -C /opt -xz
 RUN wget -O - https://github.com/vincentzwc/prebuilt-nds32-toolchain/releases/download/20180521/nds32le-linux-glibc-v3-upstream.tar.gz | tar -C /opt -xz
 
 # Update and install things from apt now