igraph: remove fop dependency and correctly generate HTML doc (#522762)

pkgs/by-name/ig/igraph/package.nix

@@ -7,12 +7,13 @@
   blas,
   cmake,
   flex,
-  fop,
   glpk,
   gmp,
   lapack,
   libxml2,
   libxslt,
+  docbook_xml_dtd_43,
+  docbook_xsl,
   llvmPackages,
   pkg-config,
   plfit,
@@ -48,9 +49,10 @@ stdenv.mkDerivation (finalAttrs: {
     bison
     cmake
     flex
-    fop
     libxml2
     libxslt
+    docbook_xml_dtd_43
+    docbook_xsl
     pkg-config
     python3
     sourceHighlight
@@ -85,6 +87,11 @@ stdenv.mkDerivation (finalAttrs: {
     "-DBUILD_SHARED_LIBS=ON"
   ];
 
+  buildFlags = [
+    "all"
+    "html"
+  ];
+
   doCheck = true;
 
   postInstall = ''