FROMLIST: lib: vdso: add support for time

FROMLIST: lib: vdso: add support for time

(cherry pick from url https://patchwork.kernel.org/patch/10053549/)

Add time() vdso support to match up with existing support in the x86's
vdso.  Currently benefitting arm and arm64 which uses the common
vgettimeofday.c implementation.  On arm provides about a ~14 fold
improvement in speed over the straight syscall, and about a ~5 fold
improvement in speed over an alternate library implementation that
relies on the vdso call to gettimeofday to fulfill the request.

We can provide __vdso_time even if we can not provide a speed
enhanced __vdso_gettimeofday.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Bug: 63737556
Bug: 20045882
Change-Id: I0bb3c6bafe57f9ed69350e2dd54edaae58316e8f