Add seccomp test support for risc64 am: 96d0f860cc am: ca349375bf am: d1d562a0d9

Original change: https://android-review.googlesource.com/c/platform/external/seccomp-tests/+/2252393

Change-Id: I44a040ab30145fd1a918d66f6beebddc8414252d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/linux/seccomp_bpf.c b/linux/seccomp_bpf.c
index 949ac25..ad7d7ce 100644
--- a/linux/seccomp_bpf.c
+++ b/linux/seccomp_bpf.c
@@ -1242,6 +1242,10 @@
 # define ARCH_REGS     s390_regs
 # define SYSCALL_NUM   gprs[2]
 # define SYSCALL_RET   gprs[2]
+#elif defined(__riscv)
+# define ARCH_REGS	struct user_regs_struct
+# define SYSCALL_NUM	a7
+# define SYSCALL_RET	a0
 #else
 # error "Do not know how to find your architecture's registers and syscalls"
 #endif