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

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

Change-Id: Ib0b8f5d7c5013b91eae6bbc3847852eb355c7714

libc/arch-mips64/syscalls/__socket.S

@@ -0,0 +1,26 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(__socket)
+    .set push
+    .set noreorder
+    li v0, __NR_socket
+    syscall
+    bnez a3, 1f
+    move a0, v0
+    j ra
+    nop
+1:
+    move t0, ra
+    bal     2f
+    nop
+2:
+    .cpsetup ra, t1, 2b
+    LA t9,__set_errno
+    .cpreturn
+    j t9
+    move ra, t0
+    .set pop
+END(__socket)
+.hidden __socket