Fix build on alpha.

Index: mpi/longlong.h
--- mpi/longlong.h.orig
+++ mpi/longlong.h
@@ -186,6 +186,7 @@ SPDX-License-Identifier: LGPL-2.1-or-later
     (pl) = __m0 * __m1; 						\
   } while (0)
 # define UMUL_TIME 46
+#if 0
 # ifndef LONGLONG_STANDALONE
 #  define udiv_qrnnd(q, r, n1, n0, d) \
   do { UDItype __r;							\
@@ -195,6 +196,7 @@ SPDX-License-Identifier: LGPL-2.1-or-later
 extern UDItype __udiv_qrnnd (UDItype *, UDItype, UDItype, UDItype);
 #  define UDIV_TIME 220
 # endif /* !LONGLONG_STANDALONE */
+#endif /* 0 */
 #endif /* __alpha */
 
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