change ln to update-alternatives, add lit and wllvm

Author: ladisgin

.github/workflows/matrix.json

@@ -1,7 +1,7 @@
 {
   "include": [
     {
-      "DOCKER_TAG": "24-11-2021",
+      "DOCKER_TAG": "18-01-2022",
       "OPERATING_SYSTEM_TAG": "18.04"
     }
   ]

docker/Dockerfile_base

@@ -11,7 +11,6 @@ FROM ubuntu:$OPERATING_SYSTEM_TAG as base_env
 LABEL maintainer="Huawei UTBot cloud team"
 SHELL ["/bin/bash", "--login", "-c"]
 
-ENV CC=gcc
 ENV UTBOT_ALL=/utbot_distr
 ENV WORKSPACE=/github/workspace/
 
@@ -28,11 +27,10 @@ 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 remove --purge -y gcc g++
 RUN apt update && apt install -y --no-install-recommends gcc-9 g++-9
-RUN ln -s /usr/bin/gcov-9 /usr/bin/gcov
-RUN ln -s /usr/bin/gcc-9 /usr/bin/gcc
-RUN ln -s /usr/bin/g++-9 /usr/bin/g++
+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
 
 # install git
 RUN apt install -y software-properties-common
@@ -109,7 +107,9 @@ USER utbot
 RUN sudo -E apt install -y --no-install-recommends curl libcap-dev libncurses5-dev unzip libtcmalloc-minimal4 libgoogle-perftools-dev libsqlite3-dev doxygen python3-pip
 ENV CURL_CA_BUNDLE=""
 RUN sudo -E pip3 install tabulate==0.8.7 \
-                         typing==3.7.4.3
+                         typing==3.7.4.3 \
+                         lit==0.11.0.post1 \
+                         wllvm==1.3.1
 
 # Install z3
 USER root
@@ -166,8 +166,7 @@ USER root
 COPY building_dependencies/patches/lit.py /usr/local/bin/lit
 RUN chmod +x /usr/local/bin/lit
 
-RUN sudo rm /usr/bin/python
-RUN sudo ln -s /usr/bin/python3 /usr/bin/python
+RUN sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 100
 
 # Download CLI11 and Rang libs for nice CLI
 RUN wget https://github.com/CLIUtils/CLI11/releases/download/v1.9.1/CLI11.hpp -P $UTBOT_ALL/cli