[BUGFIX] Register aspect autoloader check if already registered

The check, if the autoloader for the aspect is already registered,
checks only the first loader. The new implementation set a internal
flag to check the register status of the aspect SPL autoload, to
avoid problems with other SPL autoloader.

Change-Id: I8e8fa13dd90fb10d7a101fd0c88d62151f77f915
Reviewed-on: http://review.typo3.org/32780
Reviewed-by: Tim Lochmüller <tim@fruit-lab.de>
Tested-by: Tim Lochmüller <tim@fruit-lab.de>