Implement <sys/fsuid.h>.

Change-Id: I1e5e50444a1b5a430ba5b5d9b8b1d91219af5e92
diff --git a/libc/arch-x86_64/syscalls/setfsuid.S b/libc/arch-x86_64/syscalls/setfsuid.S
new file mode 100644
index 0000000..cfdb86c
--- /dev/null
+++ b/libc/arch-x86_64/syscalls/setfsuid.S
@@ -0,0 +1,15 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(setfsuid)
+    movl    $__NR_setfsuid, %eax
+    syscall
+    cmpq    $-MAX_ERRNO, %rax
+    jb      1f
+    negl    %eax
+    movl    %eax, %edi
+    call    __set_errno
+1:
+    ret
+END(setfsuid)