Mark sockets on creation (socket()) and accept4().

Remove the separate syscall for accept() and implement it as accept4(..., 0).

Change-Id: Ib0b8f5d7c5013b91eae6bbc3847852eb355c7714
diff --git a/libc/arch-arm/syscalls/__socket.S b/libc/arch-arm/syscalls/__socket.S
new file mode 100644
index 0000000..d63028b
--- /dev/null
+++ b/libc/arch-arm/syscalls/__socket.S
@@ -0,0 +1,14 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(__socket)
+    mov     ip, r7
+    ldr     r7, =__NR_socket
+    swi     #0
+    mov     r7, ip
+    cmn     r0, #(MAX_ERRNO + 1)
+    bxls    lr
+    neg     r0, r0
+    b       __set_errno
+END(__socket)