Add arch-x86_64/bionic.
This is basically half of I5de76f6c46ac87779f207d568a86bb453e2414de from
Pavel Chupin <pavel.v.chupin@intel.com>, but with the stock upstream
setjump/sigsetjmp and H.J. Lu's suggested changes to __rt_sigreturn.
Change-Id: I8167ec228faeb2065391e5bec0413cca662f3d33
diff --git a/libc/arch-x86_64/syscalls/__arch_prctl.S b/libc/arch-x86_64/syscalls/__arch_prctl.S
new file mode 100644
index 0000000..21d154c
--- /dev/null
+++ b/libc/arch-x86_64/syscalls/__arch_prctl.S
@@ -0,0 +1,17 @@
+/* autogenerated by gensyscalls.py */
+#include <asm/unistd.h>
+#include <linux/err.h>
+#include <machine/asm.h>
+
+ENTRY(__arch_prctl)
+ movl $__NR_arch_prctl, %eax
+ syscall
+ cmpq $-MAX_ERRNO, %rax
+ jb 1f
+ negl %eax
+ movl %eax, %edi
+ call __set_errno
+ orq $-1, %rax
+1:
+ ret
+END(__arch_prctl)