Move llhandle.h into llcommon; same generality as llpointer.h.

Leaving llhandle.h in llui restricts the set of viewer project directories
which could potentially use it, and there's nothing whatsoever UI-specific
about it.

indra/llcommon/CMakeLists.txt

@@ -174,6 +174,7 @@ set(llcommon_HEADER_FILES
     llfoldertype.h
     llformat.h
     llframetimer.h
+    llhandle.h
     llhash.h
     llheartbeat.h
     llhttpstatuscodes.h

indra/llui/CMakeLists.txt

@@ -155,7 +155,6 @@ set(llui_HEADER_FILES
     llflyoutbutton.h 
     llfocusmgr.h
     llfunctorregistry.h
-    llhandle.h
     llhelp.h
     lliconctrl.h
     llkeywords.h