Linux 3.15 adds support for clock_gettime, gettimeofday, and time vDSO
(commit id 37c975545ec63320789962bf307f000f08fabd48). This patch adds
GLIBC supports to use such symbol when they are avaiable.
Along with x86 vDSO support, this patch cleanup x86_64 code by moving
all common code to x86 common folder. Only init-first.c is different
between implementations.
Replace gettimeofday with __vdso_gettimeofday.
* sysdeps/unix/sysv/linux/x86_64/init-first.c (_libc_vdso_platform_setup):
Replace clock_gettime and getcpu with __vdso_clock_gettime and
__vdso_getcpu.
* sysdeps/unix/sysv/linux/x86_64/time.c (time_ifunc): Replace
time with __vdso_time.