[BUGFIX] Error handler callback causes fatal error for parse time errors

[BUGFIX] Error handler callback causes fatal error for parse time errors

TYPO3's error handler callback t3lib_error_ErrorHandler::handleError()
causes a fatal error for PHP parse time errors.

If an error occurs during parse time (like E_DEPRECATED due to
deprecated $foo =& stdClass() code), autoloading is not available
and such PHP standard class 'Exception' (extended by t3lib_exception)
is not resolvable.
This results in a fatal and misleading error
'Class "Exception" not found'
together with a not useful backtrace. Additionally this behaviour
hides the original causing error (deprecated code).

Change-Id: I4ab97c1bf2d888022369f2095285cecc5a4c54a4
Fixes: #31834
Related: #31827
Releases: 4.5, 4.6, 4.7, 6.0
Reviewed-on: http://review.typo3.org/6683
Reviewed-by: Philipp Gampe
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn