* config.sub: Add riscv-* as an alias for riscv32-*.

* testsuite/config-sub.data: Add tests.

Signed-off-by: Ben Elliston <bje@gnu.org>

config.sub

@@ -1125,6 +1125,12 @@ case $basic_machine in
 	ps2)
 		basic_machine=i386-ibm
 		;;
+	riscv)
+		basic_machine=riscv32-unknown
+		;;
+	riscv-*)
+		basic_machine=`echo "$basic_machine" | sed 's/^riscv/riscv32/'`
+		;;
 	rm[46]00)
 		basic_machine=mips-siemens
 		;;