Add correct install path to ghc

CMakeLists.txt

@@ -8,6 +8,7 @@ if(NOT (dune-common_DIR OR dune-common_ROOT OR
 endif()
 
 cmake_policy(SET CMP0074 NEW)
+cmake_policy(SET CMP0087 OLD)
 
 #find dune-common and set the module path
 find_package(dune-common REQUIRED)

lib/CMakeLists.txt

@@ -81,7 +81,7 @@ else()
 
   target_include_directories(filesystem INTERFACE
     $<BUILD_INTERFACE:${ghc_filesystem_SOURCE_DIR}/include>
-    $<INSTALL_INTERFACE:include>
+    $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>
   )
 
   target_compile_definitions(filesystem INTERFACE DUNE_COPASI_USE_FALLBACK_FILESYSTEM)