[BUG] Constant TYPO3_URL_DONATE defined twice

Constant TYPO3_URL_DONATE is defined twice. Once with
the old, simulate static URL, and once with the new, current
URL.

Change-Id: If7d2ead0e86ac93d18251db38a7c226af5903355
Resolves: #26781
Releases: 4.6, 4.5
Reviewed-on: http://review.typo3.org/2094
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Philipp Gampe
Tested-by: Philipp Gampe
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers