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>
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 151749b..f81b89f 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -333,7 +333,7 @@
 int     __set_thread_area:set_thread_area(void*) x86
 
 # vdso stuff.
-int clock_gettime(clockid_t, timespec*)                 arm,mips,mips64,x86
-int __clock_gettime:clock_gettime(clockid_t, timespec*) arm64,x86_64
-int gettimeofday(timeval*, timezone*)                   arm,mips,mips64,x86
-int __gettimeofday:gettimeofday(timeval*, timezone*)    arm64,x86_64
+int clock_gettime(clockid_t, timespec*)                 arm,mips,mips64
+int __clock_gettime:clock_gettime(clockid_t, timespec*) arm64,x86,x86_64
+int gettimeofday(timeval*, timezone*)                   arm,mips,mips64
+int __gettimeofday:gettimeofday(timeval*, timezone*)    arm64,x86,x86_64