Cleanup build config

Author: vitaut

.github/workflows/linux.yml

@@ -94,7 +94,7 @@ jobs:
     - name: Install Clang 3.6
       run: |
         sudo apt update
-        sudo apt install libtinfo5 libobjc4
+        sudo apt install libtinfo5
         # https://code.launchpad.net/ubuntu/xenial/amd64/clang-3.6/1:3.6.2-3ubuntu2
         wget --no-verbose \
           http://launchpadlibrarian.net/230019046/libffi6_3.2.1-4_amd64.deb \