Similar to commit 31ab78ae

Fixes deadlock because FileInputStream::Read() unlocks the mutex
(which was not locked) and then locks it, keeping it locked.  This can
result in a deadlock.  This happens because the archive and the file
mutex are different.

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

Avoid wasting 4 kB stack per directory level.

The check was added in commit 98fd9b7d, but there was never a
definition.

Set the Error when zzip_seek()==-1 and not on success.  Fixes a crash
after seeking.

Simplify the definition of many build options.

Has been moved to class InputStream long ago.

Remove the "whence" parameter that is not actually necessary, and only
complicates the InputStream implementations.