Fix timestamp writing

Author: Jugst3r

tools/gnatcov/ada-rts/gnatcov_rts-traces-output.adb

@@ -310,13 +310,16 @@ package body GNATcov_RTS.Traces.Output is
 
       declare
          Timestamp : Interfaces.Unsigned_64 := Exec_Date;
-         Bytes     : Uint8_Array := (1 => 0);
+         Bytes     : Uint8_Array (1 .. 8);
+         Bytes_Str : String (1 .. 8);
+         for Bytes_Str'Address use Bytes'Address;
+         pragma Import (Ada, Bytes_Str);
       begin
          for I in 1 .. 8 loop
-            Bytes (1) := Interfaces.Unsigned_8 (Timestamp mod 8);
+            Bytes (I) := Interfaces.Unsigned_8 (Timestamp mod 8);
             Timestamp := Shift_Right (Timestamp, 8);
-            Write_Bytes (Output, Bytes);
          end loop;
+         Write_Info (Output, Info_Exec_Date, Bytes_Str);
       end;
 
       Write_Info (Output, Info_User_Data, User_Data);