We used to ignore the `.gnu.hash` section, however it turns out to be
fundamental in case the ELF we're working on *defines* one or more
symbols. This has not been a problem so far since we usually work with
the main executable only, which, usually, doesn't define any dynamic
symbol. However, for example, `ls` "defines" a `getoptind` symbol (more
accurately, it clones it from libc).

To handle this situation, we replace the `.gnu.hash` with a minimal
`.hash` section. Basically, the `.hash` section should contain an hash
table. However, currently, we just create an hash table with a single
entry, which immediately triggers scanning the chain of entries
colliding in the (only) entry.