sparc-coff writing uninitialized memory

sparc-coff has a 20 byte symbol entry with an extra field, but neglects
to initialize the field.  Fix that.

	* coff/sparc.h (COFF_ADJUST_SYM_OUT_POST): Define.

include/ChangeLog

+2016-06-11  Alan Modra  <amodra@gmail.com>
+
+	* coff/sparc.h (COFF_ADJUST_SYM_OUT_POST): Define.
+
 2016-06-08  Jose E. Marchesi  <jose.marchesi@oracle.com>
 
 	* opcode/sparc.h: Add missing documentation for hyperprivileged

include/coff/sparc.h

@@ -138,6 +138,14 @@ union external_auxent
 #define	AUXENT	union external_auxent
 #define	AUXESZ	20
 
+#define COFF_ADJUST_SYM_OUT_POST(ABFD, INP, EXTP)	\
+  do							\
+    {							\
+      SYMENT *extsym = (SYMENT *) (EXTP);		\
+      extsym->padding[0] = 0;				\
+      extsym->padding[1] = 0;				\
+    } while (0)
+
 #define _ETEXT	"etext"
 
 /********************** RELOCATION DIRECTIVES **********************/