Remove obsolete link libraries

None of them are actually linked any more - most were due to using
libgit2 for masterlist updates. Also refactor the CMakeLists.txt as the
libraries are target-dependent, not compiler-dependent.

.github/workflows/ci.yml

@@ -99,12 +99,7 @@ jobs:
             doxygen \
             language-pack-el \
             language-pack-tr \
-            libbz2-dev \
-            libcurl4-gnutls-dev \
-            libhttp-parser-dev \
             libicu-dev \
-            libssh2-1-dev \
-            libssl-dev \
             g++-8
 
       - name: Run CMake

.github/workflows/release.yml

@@ -71,16 +71,11 @@ jobs:
       - name: Install APT package dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y \
+          sudo apt-get install -y --no-upgrade \
             doxygen \
             language-pack-el \
             language-pack-tr \
-            libbz2-dev \
-            libcurl4-gnutls-dev \
-            libhttp-parser-dev \
             libicu-dev \
-            libssh2-1-dev \
-            libssl-dev \
             g++-8
 
       - name: Run CMake