hash.py: observe endianness when reading hashes (#338)

hash.py: observe endianness when reading hashes (#338)

Reading the hashes from a GNUHashTable didn't properly use
the endianness of the underlying ELF file, so looking up
hashes would fail if the byte order of the analyzed file
did not match the native byte order of the current machine.

The test file consists of two functions:

int callee(){
    return 42;
}

int caller(){
    return callee();
}

and was compiled using `aarch64_be-linux-gcc` (version 8.3
on an x86_64 host) with the `-mbig-endian` and `-shared`
command line flags.