[TYPO3-core] RFC: #13262: replace hardcoded typo3/ with TYPO3_mainDir

[Benjamin Mack]

Hey,

I optimized the latest patch by adding a "strlen($BACK_PATH) > 0" check 
and added a little more in the comment.

Committed to trunk (rev. 7051).
Committed to TYPO3_4-3 (rev. 7052).

All the best,
Benni.