Remove the dependency on the non-uapi __kernel_nlink_t.

The kernel doesn't have an nlink_t; it just uses the equivalent of
uint32_t. We already had a usable __nlink_t in the C library, so
let's just define our nlink_t in terms of __nlink_t, which is what
__nlink_t was meant for anyway.

Note that our struct stat just follows the kernel, and doesn't refer
to nlink_t anyway.

Change-Id: I6f51188d188fab975e286d6f8945fe746200b8d4
DNS: make the same ip type DNS query as the interface address type

Since dns query happens on non-default interface, only query the
 address type that the interface has;otherwise the dns results
 might not be usable.

CRs-fixed: 694805
Change-Id: I4ce900507bf18a9f60a2971cf496aa7c930d540b
Revert "Disable LTO for libc and libdl. They don't play nice."

This reverts commit dbb70a66b5e8c8b0f3ce3d594809334003ead7da.