target-or32: Add linux user support

Add QEMU OpenRISC linux user support.

Signed-off-by: Jia Liu <proljc@gmail.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 539af3f..630a455 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7377,7 +7377,7 @@
     case TARGET_NR_sigaltstack:
 #if defined(TARGET_I386) || defined(TARGET_ARM) || defined(TARGET_MIPS) || \
     defined(TARGET_SPARC) || defined(TARGET_PPC) || defined(TARGET_ALPHA) || \
-    defined(TARGET_M68K) || defined(TARGET_S390X)
+    defined(TARGET_M68K) || defined(TARGET_S390X) || defined(TARGET_OPENRISC)
         ret = do_sigaltstack(arg1, arg2, get_sp_from_cpustate((CPUArchState *)cpu_env));
         break;
 #else