riscv64: add "private/bionic_asm.h".

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: treehugger
Change-Id: Iaa7d5584dfd0ec6f0cf6d3d43ae6bdf2261b12f8
diff --git a/libc/private/bionic_asm.h b/libc/private/bionic_asm.h
index d68a2d6..78e5046 100644
--- a/libc/private/bionic_asm.h
+++ b/libc/private/bionic_asm.h
@@ -45,6 +45,8 @@
 #include <private/bionic_asm_arm.h>
 #elif defined(__i386__)
 #include <private/bionic_asm_x86.h>
+#elif defined(__riscv)
+#include <private/bionic_asm_riscv64.h>
 #elif defined(__x86_64__)
 #include <private/bionic_asm_x86_64.h>
 #endif