Add accept4() syscall

Add accept4() using SYSCALLS.TXT and gensyscall

Change-Id: I6f19f29144186d15d46423e10f2cc4b4223719c6
diff --git a/libc/arch-arm/syscalls/accept4.S b/libc/arch-arm/syscalls/accept4.S
new file mode 100644
index 0000000..6d14e79
--- /dev/null
+++ b/libc/arch-arm/syscalls/accept4.S
@@ -0,0 +1,14 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(accept4)
+    mov     ip, r7
+    ldr     r7, =__NR_accept4
+    swi     #0
+    mov     r7, ip
+    cmn     r0, #(MAX_ERRNO + 1)
+    bxls    lr
+    neg     r0, r0
+    b       __set_errno
+END(accept4)