[bug][fix] platform/unix/directory.c doesn't compile under Debian Linux

[Tim Olson]

There are variable declarations in readDirectory()  which are not at 
the beginning of a block; that is illegal in ANSI C (dunno why it 
compiles OK under MacOS, which is also using gcc)?

Here is a modified version which fixes this:

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int readDirectory(int dirHandle, struct ByteArray *entNameBuffer) {
   struct dirent ent;
   struct dirent *result = &ent;
   int resultCode, entLen;

   if (dirHandle < 0)
     return -EINVAL;

#ifdef __CYGWIN__
   result = readdir(dirs[dirHandle]);
   resultCode = errno;
#else
   resultCode = readdir_r(dirs[dirHandle], result, &result);
#endif

   if (resultCode != 0) {
     /* An error situation. */
     assert(resultCode >= 0);    /* TODO: read SUSv2. The Darwin manpage 
is unclear about this */
     return -resultCode;
   }

   if (result == NULL) {
     /* End of the directory. */
     return 0;
   }

   entLen = strlen(result->d_name);
   if (entLen == 0) {
     /* Bizarre! Make up a reasonable response. */
     return -ENOENT;
   }

   assert(BYTEARRAY_LEN(entNameBuffer) >= entLen);
   memcpy(entNameBuffer->elements, result->d_name, entLen);
   return entLen;
}

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