Update config.guess and config.sub from mainstream.

Recognizes riscv32be and riscv64be.
diff --git a/build-scripts/config.guess b/build-scripts/config.guess
index f8dc455..fdfca6b 100755
--- a/build-scripts/config.guess
+++ b/build-scripts/config.guess
@@ -2,7 +2,7 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2020 Free Software Foundation, Inc.
 
-timestamp='2020-12-22'
+timestamp='2020-12-31'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1087,7 +1087,7 @@
     ppcle:Linux:*:*)
 	echo powerpcle-unknown-linux-"$LIBC"
 	exit ;;
-    riscv32:Linux:*:* | riscv64:Linux:*:*)
+    riscv32:Linux:*:* | riscv32be:Linux:*:* | riscv64:Linux:*:* | riscv64be:Linux:*:*)
 	echo "$UNAME_MACHINE"-unknown-linux-"$LIBC"
 	exit ;;
     s390:Linux:*:* | s390x:Linux:*:*)
diff --git a/build-scripts/config.sub b/build-scripts/config.sub
index 7273b76..1c22132 100755
--- a/build-scripts/config.sub
+++ b/build-scripts/config.sub
@@ -2,7 +2,7 @@
 # Configuration validation subroutine script.
 #   Copyright 1992-2020 Free Software Foundation, Inc.
 
-timestamp='2020-12-22'
+timestamp='2020-12-31'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -1230,7 +1230,7 @@
 			| powerpc | powerpc64 | powerpc64le | powerpcle | powerpcspe \
 			| pru \
 			| pyramid \
-			| riscv | riscv32 | riscv64 \
+			| riscv | riscv32 | riscv32be | riscv64 | riscv64be \
 			| rl78 | romp | rs6000 | rx \
 			| s390 | s390x \
 			| score \