libdecnumber: Prepare libdecnumber for QEMU include structure

Consistent with other libraries in QEMU, the libdecnumber header files were
placed in include/libdecnumber, separate from the C code.  This is different
from the original libdecnumber source, where they were co-located.

Change the libdecnumber source code so that it reflects this split.  Specifically,
modify directives of the form:

    #include "xxx.h"

to look like:

    #include "libdecnumber/xxx.h"

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/libdecnumber/dpd/decimal128.c b/libdecnumber/dpd/decimal128.c
index 54191aa..8f8e983 100644
--- a/libdecnumber/dpd/decimal128.c
+++ b/libdecnumber/dpd/decimal128.c
@@ -42,11 +42,11 @@
 #include <string.h>	      /* [for memset/memcpy] */
 #include <stdio.h>	      /* [for printf] */
 
-#include "dconfig.h"	      /* GCC definitions */
+#include "libdecnumber/dconfig.h"
 #define	 DECNUMDIGITS 34      /* make decNumbers with space for 34 */
-#include "decNumber.h"	      /* base number library */
-#include "decNumberLocal.h"   /* decNumber local types, etc. */
-#include "decimal128.h"	      /* our primary include */
+#include "libdecnumber/decNumber.h"
+#include "libdecnumber/decNumberLocal.h"
+#include "libdecnumber/dpd/decimal128.h"
 
 /* Utility routines and tables [in decimal64.c] */
 extern const uInt   COMBEXP[32], COMBMSD[32];