libc: arch-x86: implement kernel vdso time functions

This patch give the possibility of time vdso support on 32bit kernel.
If the 32bit x86 kernel provides gettimeofday() and clock_gettime()
primitives in vdso. In this case make bionic use them. If the kernel
doesn't provide them, fallback to the legacy system call versions.

Change-Id: I87b772a9486fa356903e1f98f486ab9eb0b6f6f7
Signed-off-by: Robert Jarzmik <robert.jarzmik@intel.com>
Signed-off-by: Mingwei Shi <mingwei.shi@intel.com>