base: Install libc6-dbg:i386

In tests, users may see a segfault in CI which they may not be able to
reproduce locally (due to having a different OS).
A user may try to get more info in the CI by running the test with
valgrind. But for valgrind to run with 32bit targets we need
libc6-dbg:i386 installed.
So let's install it by default so it is ready for users.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

Dockerfile.base

@@ -96,7 +96,7 @@ RUN if [ "${HOSTTYPE}" = "x86_64" ]; then \
  apt-get -y update && \
  apt-get -y upgrade && \
  apt-get install --no-install-recommends -y \
- libsdl2-dev:i386 libfuse-dev:i386 \
+ libsdl2-dev:i386 libfuse-dev:i386 libc6-dbg:i386 \
  ; fi
 
 # Initialise system locale