Link headers to exported library

This allows to use the CoolProp library
from cmake by simply linking against it,
without to specify any additional include paths
for the coolprop public header file.

Addresses CoolProp#2144

CMakeLists.txt

@@ -545,8 +545,7 @@ if(COOLPROP_OBJECT_LIBRARY
       DESTINATION
         static_library/${CMAKE_SYSTEM_NAME}/${BITNESS}bit_${CMAKE_CXX_COMPILER_ID}_${CMAKE_CXX_COMPILER_VERSION}
     )
-    install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${COOLPROP_LIBRARY_HEADER}
-            DESTINATION static_library)
+    set(CoolPropLibDestination "static_library")
   elseif(COOLPROP_SHARED_LIBRARY)
     list(APPEND APP_SOURCES
          "${CMAKE_CURRENT_SOURCE_DIR}/${COOLPROP_LIBRARY_SOURCE}")
@@ -556,8 +555,7 @@ if(COOLPROP_OBJECT_LIBRARY
       EXPORT CoolProp-targets
       DESTINATION shared_library/${CMAKE_SYSTEM_NAME}/${BITNESS}bit${CONVENTION}
     )
-    install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${COOLPROP_LIBRARY_HEADER}
-            DESTINATION shared_library)
+    set(CoolPropLibDestination "shared_library")
     set_property(
       TARGET CoolPropLib
       APPEND_STRING
@@ -600,6 +598,15 @@ if(COOLPROP_OBJECT_LIBRARY
 
     set(COOLPROP_CMAKE_DIR "lib/cmake/CoolProp")
 
+    # install the public header file
+    install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/${COOLPROP_LIBRARY_HEADER}
+            DESTINATION ${CoolPropLibDestination})
+
+    # link header file to library
+    target_include_directories(CoolPropLib PUBLIC
+        $<INSTALL_INTERFACE:${CoolPropLibDestination}>
+    )
+
     # install exports
     install (
         EXPORT CoolProp-targets