Add a build-condition for disabling building documentation

The optional documentation distributed within doc subpackage requires
doxygen and graphviz at build time. That is an obstacle when building
jsoncpp for modular Fedora when the dependecies are not yet available.

This patch introduces a build-time condition that allows to disable
generating the documentation while building in normal Fedora is
unchanged.

jsoncpp.spec

@@ -1,3 +1,6 @@
+# Build documentation in HTML with images
+%bcond_without jsoncpp_enables_doc
+
 %global jsondir json
 
 Name:       jsoncpp
@@ -10,10 +13,12 @@ URL:        https://github.com/open-source-parsers/%{name}
 Source0:    %{url}/archive/%{version}.tar.gz#/%{name}-%{version}.tar.gz
 
 BuildRequires:  cmake >= 3.1
+%if %{with jsoncpp_enables_doc}
 BuildRequires:  doxygen
 BuildRequires:  graphviz
 BuildRequires:  hardlink
 BuildRequires:  python3-devel
+%endif
 
 %description
 %{name} is an implementation of a JSON (http://json.org) reader and writer in
@@ -30,18 +35,22 @@ Requires:   %{name}%{?_isa} = %{version}-%{release}
 This package contains the development headers and library for %{name}.
 
 
+%if %{with jsoncpp_enables_doc}
 %package doc
 Summary:    Documentation for %{name}
 BuildArch:  noarch
 
 %description doc
 This package contains the documentation for %{name}.
+%endif
 
 
 %prep
 %autosetup -p 1
+%if %{with jsoncpp_enables_doc}
 doxygen -s -u doc/doxyfile.in
 sed -i -e 's!^DOT_FONTNAME.*=.*!DOT_FONTNAME =!g' doc/doxyfile.in
+%endif
 
 
 %build
@@ -58,19 +67,23 @@ popd
 
 %make_build -C %{_target_platform}
 
+%if %{with jsoncpp_enables_doc}
 # Build the doc
 %{__python3} doxybuild.py --with-dot --doxygen %{_bindir}/doxygen
+%endif
 
 
 %install
 %make_install -C %{_target_platform}
 
+%if %{with jsoncpp_enables_doc}
 mkdir -p %{buildroot}%{_docdir}/%{name}/html
 for f in README.md ; do
     install -p -m 0644 $f %{buildroot}%{_docdir}/%{name}
 done
 install -p -m 0644 dist/doxygen/*/*.{html,png} %{buildroot}%{_docdir}/%{name}/html
 hardlink -cfv %{buildroot}%{_docdir}/%{name}
+%endif
 
 
 %check
@@ -83,9 +96,11 @@ hardlink -cfv %{buildroot}%{_docdir}/%{name}
 
 %files
 %license AUTHORS LICENSE
+%if %{with jsoncpp_enables_doc}
 %doc %dir %{_docdir}/%{name}
 %doc %{_docdir}/%{name}/README.md
 %exclude %{_docdir}/%{name}/html
+%endif
 %{_libdir}/lib%{name}.so.*
 
 
@@ -96,9 +111,11 @@ hardlink -cfv %{buildroot}%{_docdir}/%{name}
 %{_libdir}/pkgconfig/jsoncpp.pc
 
 
+%if %{with jsoncpp_enables_doc}
 %files doc
 %license %{_datadir}/licenses/%{name}*
 %doc %{_docdir}/%{name}*
+%endif
 
 
 %changelog