Correct use of perl stack macros

Further to pull #49 this is the result of an audit of the use of perl
stack macros. There were several cases where PUTBACK was being called
where the stack pointer could be out-of-date.

Also some misc. cleanup where the macros were used needlessly.

src/perl/textui/Statusbar.xs

@@ -89,7 +89,6 @@ static void perl_statusbar_event(char *function, SBAR_ITEM_REC *item,
 		}
 	}
 
-	PUTBACK;
 	FREETMPS;
 	LEAVE;
 }