support/testing/tests/package/test_gdb.py: fix ARC test
Since the disabling of the Synopsys ARC toolchain in
11a8cdd2bbbd0ef4adf600e4792d75f6f2122ec8, the test
tests.package.test_gdb.TestGdbArc was failing as it was relying on
this external toolchain.
Let's switch the test to use BR2_archs38, which allows to use a
Bootlin toolchain.
Fixes:
https://gitlab.com/buildroot.org/buildroot/-/jobs/8892696282
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Julien Olivain <ju.o@free.fr>
Thomas Petazzoni