fbc: internal change - discard result in rtlStrAssign()

Author: jayrm

src/compiler/rtl-string.bas

@@ -2554,7 +2554,10 @@ function rtlStrAssign _
 		exit function
 	end if
 
-	''
+	'' always discard result, even though actual rtlib returns a ptr to destination
+	'' it will never be used anywhere
+	astSetType( proc, FB_DATATYPE_VOID, NULL )
+
 	function = proc
 
 end function