Introduce netd_client, a dynamic library that talks to netd.

The library exists outside bionic. It is dynamically loaded, to replace selected
standard socket syscalls with versions that talk to netd.

Change connect() to use the library if available.

(cherry picked from commit 3a6b627a14df8111b03e452f2df4b5f4938e0e49)

Change-Id: Ib6198e19dbc306521a26fcecfdf6e8424d163fc9
diff --git a/libc/arch-arm64/syscalls/__connect.S b/libc/arch-arm64/syscalls/__connect.S
new file mode 100644
index 0000000..c46f418
--- /dev/null
+++ b/libc/arch-arm64/syscalls/__connect.S
@@ -0,0 +1,22 @@
+/* Generated by gensyscalls.py. Do not edit. */
+
+#include <private/bionic_asm.h>
+
+ENTRY(__connect)
+    stp     x29, x30, [sp, #-16]!
+    mov     x29,  sp
+    str     x8,       [sp, #-16]!
+
+    mov     x8, __NR_connect
+    svc     #0
+
+    ldr     x8,       [sp], #16
+    ldp     x29, x30, [sp], #16
+
+    cmn     x0, #(MAX_ERRNO + 1)
+    cneg    x0, x0, hi
+    b.hi    __set_errno
+
+    ret
+END(__connect)
+.hidden __connect