libdecnumber: Don't fool around with guards to avoid #include

Some libdecnumber headers avoid including decNumber.h or decContext.h
again by checking their header guards.  Don't.  Including them
multiple times is safe, and the compiler can do it efficiently.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
diff --git a/include/libdecnumber/dpd/decimal128.h b/include/libdecnumber/dpd/decimal128.h
index 7d9ee24..13d1ae8 100644
--- a/include/libdecnumber/dpd/decimal128.h
+++ b/include/libdecnumber/dpd/decimal128.h
@@ -59,9 +59,7 @@
   #ifndef DECNUMDIGITS
     #define DECNUMDIGITS DECIMAL128_Pmax /* size if not already defined*/
   #endif
-  #ifndef DECNUMBER
-    #include "libdecnumber/decNumber.h"
-  #endif
+  #include "libdecnumber/decNumber.h"
 
   /* Decimal 128-bit type, accessible by bytes			      */
   typedef struct {