Drupal: Fixed registration form terms-of-use checkbox

[drshawnkwang]

Description of the Change
Fixes broken user registration form.

Release Notes
N/A

https://dev.gridrepublic.org/browse/DBOINCP-497

[brevilo]

Just to make sure, boincuser_termsofuse_form_validate() shouldn't be used here?

[drshawnkwang]

No, that function is for a second form that is separate. I believe that form is for users who had accounts before terms-of-use was implemented. They are forced to see the form when the login. It has the same construct. That was the bug: I changed the check if-statement in the function boincuser_termsofuse_form_validate and not the other (or this, or relevant) boincuser_register_validate, which is being fixed in this PR.

[brevilo]

Yeah, I understand the solution but just wanted to avoid the apparent code redundancy. But agreed, that could be followed up separately.