bp_has_activities() should check if the groups component is active before using one of its functions

[imath]

Since r9536, bp_has_activities() is using groups_get_current_group() at line 625. The problem is: when the Groups component is not active, we get a fatal error as the function is not available.

I suggest to use a bp_is_active() check to avoid it.

[imath]

Well actually, using bp_is_group() would be best, see .02.patch

[imath]

In 9569:

Activity: in bp_has_activities() use bp_is_group() instead of groups_get_current_group()

Since r9536, bp_has_activities() is using the groups_get_current_group() function, which needs the Groups component to be active. There can be cases when this component has not been activated by the community administrator. In such cases, using this function is generating a fatal error. Using bp_is_group() is avoiding this error.

Fixes #6268