Fix for EXP-140 -- After logging into Skylight Viewer - User is required to click on Viewer window before using movement keys / flying

In LLMenuHolderGL::handleKey(), in the highlightNextItem() case, don't return true if highlightNextItem() did nothing.

Reviewed by Richard.

indra/llui/llmenugl.cpp

@@ -3460,8 +3460,10 @@ BOOL LLMenuHolderGL::handleKey(KEY key, MASK mask, BOOL called_from_parent)
 			else
 			{
 				//highlight first enabled one
-				pMenu->highlightNextItem(NULL);
-				handled = true;
+				if(pMenu->highlightNextItem(NULL))
+				{
+					handled = true;
+				}
 			}
 		}
 	}