igraph: random improvements

* remove outdated comment
* use plfit from Nixpkgs
* unconditionally enable OpenMP

pkgs/development/libraries/igraph/default.nix

@@ -12,7 +12,9 @@
 , lapack
 , libxml2
 , libxslt
+, llvmPackages
 , pkg-config
+, plfit
 , python3
 , sourceHighlight
 , suitesparse
@@ -30,10 +32,6 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-SL9PcT18vFvykCv4VRXxXtlcDAcybmwEImnnKXMciFQ=";
   };
 
-  # Normally, igraph wants us to call bootstrap.sh, which will call
-  # tools/getversion.sh. Instead, we're going to put the version directly
-  # where igraph wants, and then let autoreconfHook do the rest of the
-  # bootstrap. ~ C.
   postPatch = ''
     echo "${version}" > IGRAPH_VERSION
   '' + lib.optionalString stdenv.isAarch64 ''
@@ -65,7 +63,10 @@ stdenv.mkDerivation rec {
     gmp
     lapack
     libxml2
+    plfit
     suitesparse
+  ] ++ lib.optionals stdenv.cc.isClang [
+    llvmPackages.openmp
   ];
 
   cmakeFlags = [
@@ -75,8 +76,10 @@ stdenv.mkDerivation rec {
     "-DIGRAPH_USE_INTERNAL_GLPK=OFF"
     "-DIGRAPH_USE_INTERNAL_CXSPARSE=OFF"
     "-DIGRAPH_USE_INTERNAL_GMP=OFF"
+    "-DIGRAPH_USE_INTERNAL_PLFIT=OFF"
     "-DIGRAPH_GLPK_SUPPORT=ON"
     "-DIGRAPH_GRAPHML_SUPPORT=ON"
+    "-DIGRAPH_OPENMP_SUPPORT=ON"
     "-DIGRAPH_ENABLE_LTO=AUTO"
     "-DIGRAPH_ENABLE_TLS=ON"
     "-DBUILD_SHARED_LIBS=ON"