dwarf2out.c: fix jit issue with early_dwarf_finished

All of the jit testcases that generate debuginfo appear to have been
failing since r240228 on their 2nd in-process iteration on this
assertion in set_early_dwarf's ctor:

      gcc_assert (! early_dwarf_finished);

Root cause is that the global is never reset at the end of compilation,
which this patch fixes in the obvious way.

gcc/ChangeLog:
	* dwarf2out.c (dwarf2out_c_finalize): Reset early_dwarf and
	early_dwarf_finished.

From-SVN: r243136

gcc/ChangeLog

+2016-12-01  David Malcolm  <dmalcolm@redhat.com>
+
+	* dwarf2out.c (dwarf2out_c_finalize): Reset early_dwarf and
+	early_dwarf_finished.
+
 2016-12-01  Eric Botcazou  <ebotcazou@adacore.com>
             David S. Miller  <davem@davemloft.net>
 

gcc/dwarf2out.c

@@ -29830,6 +29830,9 @@ dwarf2out_c_finalize (void)
   cold_text_section = NULL;
   current_unit_personality = NULL;
 
+  early_dwarf = false;
+  early_dwarf_finished = false;
+
   next_die_offset = 0;
   single_comp_unit_die = NULL;
   comdat_type_list = NULL;