software/theia: add clangd for C/C++ language services

software/theia/software.cfg

@@ -10,6 +10,7 @@ extends =
    ../../component/vim/buildout.cfg
    ../../component/curl/buildout.cfg
    ../../component/coreutils/buildout.cfg
+   ../../component/clang-tools-extra/buildout.cfg
    ../../stack/slapos.cfg
    ../../stack/monitor/buildout.cfg
    ./gowork.cfg
@@ -329,7 +330,7 @@ template =
   inline:
   #!/bin/bash
   . ${gowork:env.sh}
-  export PATH=${python-language-server:location}/bin/:${cli-utilities:PATH}:$PATH
+  export PATH=${python-language-server:location}/bin/:${clangd:location}/bin/:${cli-utilities:PATH}:$PATH
   export THEIA_DEFAULT_PLUGINS="local-dir:${theia:THEIA_DEFAULT_PLUGINS}"
   # reset PS1 from gowork
   export PS1='$ '