install multilib before llvm

docker/Dockerfile_base

@@ -23,8 +23,9 @@ RUN echo "check_certificate = off" > /etc/wgetrc
 
 # We use C++ 17 for UnitTestBot, it is available in gcc-9; default gcc for ubuntu:18.04 is gcc-7
 RUN add-apt-repository ppa:ubuntu-toolchain-r/test
-RUN apt update && apt install -y --no-install-recommends gcc-9 g++-9
-# Skip 32bits libs installation before LLVM compilation
+RUN apt update && apt install -y --no-install-recommends gcc-9 g++-9 gcc-multilib g++-multilib gcc-9-multilib g++-9-multilib
+
+# Set gcc-9 as default gcc version
 RUN sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 100
 RUN sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-9 100
 RUN sudo update-alternatives --install /usr/bin/gcov gcov /usr/bin/gcov-9 100
@@ -211,9 +212,6 @@ RUN git clone -b klee_uclibc_v1.2 https://github.com/klee/klee-uclibc.git $UTBOT
 WORKDIR $UTBOT_ALL/klee-uclibc
 RUN ./configure --make-llvm-lib && make -j`nproc`
 
-# Install 32bits libs AFTER LLVM compilation
-RUN apt update && apt install -y --no-install-recommends gcc-multilib g++-multilib gcc-9-multilib g++-9-multilib
-
 # Download library for access private members
 RUN git clone https://github.com/martong/access_private.git $UTBOT_ALL/access_private