Fix rl78 port WRT fallthru and sprintf warnings

[Jeff Law]

rl78_calclate_death_nodes, with one exception wants to treat JUMP_INSNs 
and CALL_INSNs the same.  Naturally it's implemented with a case 
statement like

  case JUMP_INSN:
    <special case code>
  case CALL_INSN:
    <common code>

We're just missing the fallthru comment to silence the warning.

Like the stormy16, rl78 gets the buffer size wrong for ctor/dtor sections.

This patch fixes both issues.  Installed on the trunk.

Jeff
commit 7432dcb6fb3b23ce80d6631691d0a8150255cd93
Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Wed Oct 26 15:42:11 2016 +0000

        * config/rl78/rl78.c (rl78_calculate_death_notes): Add fallthru
        comment.
        (rl78_asm_ctor_dtor): Increase buffer size.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@241565 
138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d778e95..5214b9d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2016-10-26  Jeff Law  <l...@redhat.com>
 
+       * config/rl78/rl78.c (rl78_calculate_death_notes): Add fallthru
+       comment.
+       (rl78_asm_ctor_dtor): Increase buffer size.
+
        * config/stormy16/stormy16.c (xstormy16_asm_output_destrutor): Increase
        buffer size.
        (xstormy16_asm_output_constructor): Likewise.
diff --git a/gcc/config/rl78/rl78.c b/gcc/config/rl78/rl78.c
index 08ab899..5375e18 100644
--- a/gcc/config/rl78/rl78.c
+++ b/gcc/config/rl78/rl78.c
@@ -3863,6 +3863,7 @@ rtx_insn *insn;
                 after this pass.  */
              break;
            }
+         /* FALLTHRU */
        case CALL_INSN:
          memset (dead, 0, sizeof (dead));
          break;
@@ -4657,7 +4658,7 @@ rl78_asm_ctor_dtor (rtx symbol, int priority, bool 
is_ctor)
     {
       /* This section of the function is based upon code copied
         from: gcc/varasm.c:get_cdtor_priority_section().  */
-      char buf[16];
+      char buf[18];
 
       sprintf (buf, "%s.%.5u", is_ctor ? ".ctors" : ".dtors",
               MAX_INIT_PRIORITY - priority);