Add __tls_get_addr for riscv64.

We added this symbol somewhat inconsistently, with arm and x86-64 in one
release and arm64 in another. It doesn't really matter where we add
riscv64 (since there was no riscv64 at either of these now-historical
API levels), so arbitrarily go with the majority.

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: I1ef1e0ebdbece728aaef52c08ee57cca1197cb95
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index 7bcee9d..dc1b6f6 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1449,7 +1449,7 @@
     ___tls_get_addr; # x86
     __aeabi_read_tp; # arm
     __res_randomid;
-    __tls_get_addr; # arm x86_64
+    __tls_get_addr; # arm riscv64 x86_64
     android_fdsan_close_with_tag;
     android_fdsan_create_owner_tag;
     android_fdsan_exchange_owner_tag;