Replace custom %{bashcompdir} macro with %{bash_completions_dir}

$ pkg-config --variable=completionsdir bash-completion
    /usr/share/bash-completion/completions
    $ rpm --eval '%{bash_completions_dir}'
    /usr/share/bash-completion/completions

python-pip.spec

@@ -10,8 +10,6 @@
 %global upstream_version %{base_version}%{?prerel}
 %global python_wheel_name %{srcname}-%{upstream_version}-py3-none-any.whl
 
-%global bashcompdir %(pkg-config --variable=completionsdir bash-completion 2>/dev/null)
-
 Name:           python-%{srcname}
 Version:        %{base_version}%{?prerel:~%{prerel}}
 Release:        5%{?dist}
@@ -282,15 +280,15 @@ done
 popd
 %endif
 
-mkdir -p %{buildroot}%{bashcompdir}
+mkdir -p %{buildroot}%{bash_completions_dir}
 PYTHONPATH=%{buildroot}%{python3_sitelib} \
     %{buildroot}%{_bindir}/pip completion --bash \
-    > %{buildroot}%{bashcompdir}/pip3
+    > %{buildroot}%{bash_completions_dir}/pip3
 
 # Make bash completion apply to all the 5 symlinks we install
 sed -i -e "s/^\\(complete.*\\) pip\$/\\1 pip pip{,-}{3,%{python3_version}}/" \
     -e s/_pip_completion/_pip3_completion/ \
-    %{buildroot}%{bashcompdir}/pip3
+    %{buildroot}%{bash_completions_dir}/pip3
 
 
 # Provide symlinks to executables to comply with Fedora guidelines for Python
@@ -345,8 +343,8 @@ pytest_k='not completion'
 %{_bindir}/pip%{python3_version}
 %{_bindir}/pip-%{python3_version}
 %{python3_sitelib}/pip*
-%dir %{bashcompdir}
-%{bashcompdir}/pip3
+%dir %{bash_completions_dir}
+%{bash_completions_dir}/pip3
 
 %if %{with doc}
 %files doc