commonio: free removed database entries

commonio: free removed database entries

Free the actual struct of the removed entry.

Example userdel report:

    Direct leak of 40 byte(s) in 1 object(s) allocated from:
        #0 0x55b230efe857 in reallocarray (./src/userdel+0xda857)
        #1 0x55b230f6041f in mallocarray ./lib/./alloc.h:97:9
        #2 0x55b230f6041f in commonio_open ./lib/commonio.c:563:7
        #3 0x55b230f39098 in open_files ./src/userdel.c:555:6
        #4 0x55b230f39098 in main ./src/userdel.c:1189:2
        #5 0x7f9b48c64189 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16