Remove the last uses of mktemp and unlink/delete.

* src/files.c (fdefines, ftable): Removed.
(defines_ostack, table_obstack): New.
Adjust dependencies of the former into uses of the latter.
* src/output.c (output_short_or_char_table, output_short_table):
Convert to using obstacks.
* src/reader.c (copy_comment2): Accept one FILE * and two
obstacks.
(output_token_defines, reader_output_yylsp): Use obstacks.
* src/system.h (obstack_fgrow3): New.

src/system.h

@@ -187,3 +187,10 @@ do {						\
   sprintf (buf, Format, Arg1, Arg2);		\
   obstack_grow (Obs, buf, strlen (buf));	\
 } while (0)
+
+#define obstack_fgrow3(Obs, Format, Arg1, Arg2, Arg3)	\
+do {							\
+  char buf[4096];					\
+  sprintf (buf, Format, Arg1, Arg2, Arg3);		\
+  obstack_grow (Obs, buf, strlen (buf));		\
+} while (0)