liblinear: fix soname path names on linux

pkgs/development/libraries/liblinear/default.nix

@@ -18,17 +18,19 @@ stdenv.mkDerivation rec {
     libSuff = stdenv.hostPlatform.extensions.sharedLibrary;
   in ''
     mkdir -p $out/lib $out/bin $out/include
-    cp liblinear.so.3 $out/lib/liblinear.3${libSuff}
-    ln -s $out/lib/liblinear.3${libSuff} $out/lib/liblinear${libSuff}
+    ${if stdenv.isDarwin then ''
+      cp liblinear.so.3 $out/lib/liblinear.3.dylib
+      ln -s $out/lib/liblinear.3.dylib $out/lib/liblinear.dylib
+      install_name_tool -id liblinear.3.dylib $out/lib/liblinear.3.dylib
+    '' else ''
+      cp liblinear.so.3 $out/lib/liblinear.so.3
+      ln -s $out/lib/liblinear.so.3 $out/lib/liblinear.so
+    ''}
     cp train $out/bin/liblinear-train
     cp predict $out/bin/liblinear-predict
     cp linear.h $out/include
   '';
 
-  postFixup = stdenv.lib.optionalString stdenv.isDarwin ''
-    install_name_tool -id liblinear.3.dylib $out/lib/liblinear.3.dylib
-  '';
-
   meta = with stdenv.lib; {
     description = "A library for large linear classification";
     homepage = https://www.csie.ntu.edu.tw/~cjlin/liblinear/;