Set install of the docs to DOCDIR
--- libgaminggear-0.10.0.orig/include/gaminggear/CMakeLists.txt 2015-06-28 12:46:22.615985840 +0100
+++ libgaminggear-0.10.0/include/gaminggear/CMakeLists.txt      2015-06-28 13:01:35.511970664 +0100
@@ -14,10 +14,10 @@ IF(WITH_DOC)
     DEPENDS
       ${CMAKE_CURRENT_BINARY_DIR}/html/index.html
   )
-  
+
   INSTALL(
     DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/html
-    DESTINATION share/doc/libgaminggear
+    DESTINATION ${DOCDIR}
   )
 ENDIF()