[SECURITY] Fix open redirection in openid extension

[SECURITY] Fix open redirection in openid extension

The eID script of the openid extension does not
validate the given redirect url, leading to
an open redirection vulnerability.

Add and verify hmac of the redirect url.

Change-Id: I0d65390b61dd5cf92151d36e490a194624b98b8f
Fixes: #54099
Releases: 6.2, 6.1, 6.0, 4.7, 4.5
Security-Commit: 5c6a45c0f843a93ab048a3df4bb352b8e02099b2
Security-Bulletin: TYPO3-CORE-SA-2013-004
Reviewed-on: https://review.typo3.org/26220
Reviewed-by: Oliver Hader
Tested-by: Oliver Hader