riscv64 setjmp.

Signed-off-by: Mao Han <han_mao@linux.alibaba.com>
Signed-off-by: Xia Lifang <lifang_xia@linux.alibaba.com>
Signed-off-by: Chen Guoyin <chenguoyin.cgy@linux.alibaba.com>
Signed-off-by: Wang Chen <wangchen20@iscas.ac.cn>
Signed-off-by: Lu Xufan <luxufan@iscas.ac.cn>
Test: m
Change-Id: I02cf117f67bda74516e4de8cd6f4c05efdb9a85b
diff --git a/libc/include/setjmp.h b/libc/include/setjmp.h
index c2a9544..a3de9c7 100644
--- a/libc/include/setjmp.h
+++ b/libc/include/setjmp.h
@@ -52,6 +52,8 @@
 #define _JBLEN 64
 #elif defined(__i386__)
 #define _JBLEN 10
+#elif defined(__riscv)
+#define _JBLEN 29
 #elif defined(__x86_64__)
 #define _JBLEN 11
 #endif