libdecnumber: Clean up includes

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/libdecnumber/dpd/decimal128.c b/libdecnumber/dpd/decimal128.c
index 7551b7c..ca4764e 100644
--- a/libdecnumber/dpd/decimal128.c
+++ b/libdecnumber/dpd/decimal128.c
@@ -39,8 +39,7 @@
 /*								      */
 /* Error handling is the same as decNumber (qv.).		      */
 /* ------------------------------------------------------------------ */
-#include <string.h>	      /* [for memset/memcpy] */
-#include <stdio.h>	      /* [for printf] */
+#include "qemu/osdep.h"
 
 #include "libdecnumber/dconfig.h"
 #define	 DECNUMDIGITS 34      /* make decNumbers with space for 34 */