cmake: use LIBMRN_DIR_PREFIX not to separate read_file_list and REGEX_REPLACE
cmake: use LIBMRN_DIR_PREFIX not to separate read_file_list and REGEX_REPLACE

naoa/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,yoku0825/mroonga,naoa/mroonga,naoa/mroonga,yoku0825/mroonga,yoku0825/mroonga,mroonga/mroonga,naoa/mroonga,mroonga/mroonga,naoa/mroonga,yoku0825/mroonga,yoku0825/mroonga