libcork: fix paths in pkg-config file

pkgs/development/libraries/libcork/default.nix

@@ -16,14 +16,20 @@ stdenv.mkDerivation rec {
     sha256 = "152gqnmr6wfmflf5l6447am4clmg3p69pvy3iw7yhaawjqa797sk";
   };
 
-  # N.B. We need to create this file, otherwise it tries to use git to
-  # determine the package version, which we do not want.
-  #
-  # N.B. We disable tests by force, since their build is broken.
   postPatch = ''
+    # N.B. We need to create this file, otherwise it tries to use git to
+    # determine the package version, which we do not want.
     echo "${version}" > .version-stamp
     echo "${version}" > .commit-stamp
+
+    # N.B. We disable tests by force, since their build is broken.
     sed -i '/add_subdirectory(tests)/d' ./CMakeLists.txt
+
+    # https://github.com/dcreager/libcork/issues/173
+    substituteInPlace cmake/FindCTargets.cmake \
+      --replace '\$'{exec_prefix}/'$'{CMAKE_INSTALL_LIBDIR} '$'{CMAKE_INSTALL_FULL_LIBDIR} \
+      --replace '\$'{prefix}/'$'{CMAKE_INSTALL_INCLUDEDIR} '$'{CMAKE_INSTALL_FULL_INCLUDEDIR} \
+      --replace '\$'{datarootdir}/'$'{base_docdir} '$'{CMAKE_INSTALL_FULL_DOCDIR}
   '';
 
   nativeBuildInputs = [ cmake pkg-config ];