cmake: remove needless cache

CMakeLists.txt

@@ -68,15 +68,12 @@ set(GRN_STACK_SIZE
   CACHE STRING
   "DANGER!!! groonga stack size. Normarlly, you should not change this variable.")
 set(GRN_RELATIVE_PLUGINS_DIR
-  "${GRN_PROJECT_NAME}/plugins"
-  CACHE PATH "groonga plugins' relative directory")
+  "${GRN_PROJECT_NAME}/plugins")
 set(GRN_PLUGINS_DIR
-  "${LIB_DIR}/${GRN_RELATIVE_PLUGINS_DIR}"
-  CACHE PATH "groonga plugins' directory")
+  "${LIB_DIR}/${GRN_RELATIVE_PLUGINS_DIR}")
 set(GRN_PLUGIN_SUFFIX "${CMAKE_SHARED_MODULE_SUFFIX}")
 set(GRN_DLL_FILENAME
-  "${CMAKE_SHARED_LIBRARY_PREFIX}groonga${CMAKE_SHARED_LIBRARY_SUFFIX}"
-  CACHE PATH "groonga DLL filename")
+  "${CMAKE_SHARED_LIBRARY_PREFIX}groonga${CMAKE_SHARED_LIBRARY_SUFFIX}")
 set(GRN_QUERY_EXPANDER_TSV_RELATIVE_SYNONYMS_FILE "synonyms.tsv")
 set(GRN_QUERY_EXPANDER_TSV_SYNONYMS_FILE
   "${GRN_DATA_DIR}/${GRN_QUERY_EXPANDER_TSV_RELATIVE_SYNONYMS_FILE}")