Fix INCLUDE_INSTALL_DIR

CMakeLists.txt

@@ -50,7 +50,7 @@ if(NOT DEFINED LIB_INSTALL_DIR)
 endif(NOT DEFINED LIB_INSTALL_DIR)
 
 if(NOT DEFINED INCLUDE_INSTALL_DIR)
-    set(INCLUDE_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/include/${PACKAGE_TARNAME}")
+    set(INCLUDE_INSTALL_DIR "${CMAKE_INSTALL_PREFIX}/include")
 endif(NOT DEFINED INCLUDE_INSTALL_DIR)
 
 if(NOT DEFINED LOCALE_INSTALL_DIR)