Fixed bug EXT-4580 (Duplicated avatar's name appears in 'Group invitation'...

Fixed bug EXT-4580 (Duplicated avatar's name appears in 'Group invitation' floater if use context menu for invitation).
Because duplicated postBuild() calls, the "OK" button callback was set and *called* twice.

--HG--
branch : product-engine

indra/newview/llfloatergroups.cpp

@@ -75,7 +75,7 @@ LLFloaterGroupPicker::~LLFloaterGroupPicker()
 void LLFloaterGroupPicker::setPowersMask(U64 powers_mask)
 {
 	mPowersMask = powers_mask;
-	postBuild();
+	init_group_list(getChild<LLScrollListCtrl>("group list"), gAgent.getGroupID(), mPowersMask);
 }