'Get address of main function of stripped ELF file
Returns:
- main function address (Int)'

@memoized
def main_entry(self):

    refs = self.xrefs('__libc_start_main@plt')
    if refs:
        inst = self.prev_inst(refs[0][0])
        if inst:
            addr = re.search('.*(0x.*)', inst[0][1])
            if addr:
                return to_int(addr.group(1))
    return None
