readelf: Fix double fclose for bad file without magic number
    
    As seen on f33, `touch empty && readelf -h empty` SIGABRT'ed with
    
    > readelf: empty: Error: Failed to read file's magic number
    > free(): double free detected in tcache 2
    
    at
    
    > #0  0x00007ffff7def9d5 in raise () from /lib64/libc.so.6
    > #1  0x00007ffff7dd88a4 in abort () from /lib64/libc.so.6
    > #2  0x00007ffff7e31f27 in __libc_message () from /lib64/libc.so.6
    > #3  0x00007ffff7e39c1c in malloc_printerr () from /lib64/libc.so.6
    > #4  0x00007ffff7e3b6ec in _int_free () from /lib64/libc.so.6
    > #5  0x00007ffff7e278a3 in fclose@@GLIBC_2.2.5 () from /lib64/libc.so.6
    > #6  0x000055555555da51 in process_file (file_name=<optimized out>) at /usr/src/debug/binutils-2.35-15.fc33.x86_64/binutils/readelf.c:20821
    > #7  main (argc=3, argv=0x7fffffffe0c8) at /usr/src/debug/binutils-2.35-15.fc33.x86_64/binutils/readelf.c:20893