Use VDSO for clock_gettime(2) and gettimeofday(2).

Bug: 15387103

(cherry picked from commit 625993dfbb085a3cde7492eda8ec1cdc1ee39a78)

Change-Id: I0e156d7049ba1495902259071a96936592e74025
diff --git a/libc/arch-arm64/syscalls/clock_gettime.S b/libc/arch-arm64/syscalls/__clock_gettime.S
similarity index 76%
rename from libc/arch-arm64/syscalls/clock_gettime.S
rename to libc/arch-arm64/syscalls/__clock_gettime.S
index ffdde57..f346648 100644
--- a/libc/arch-arm64/syscalls/clock_gettime.S
+++ b/libc/arch-arm64/syscalls/__clock_gettime.S
@@ -2,7 +2,7 @@
 
 #include <private/bionic_asm.h>
 
-ENTRY(clock_gettime)
+ENTRY(__clock_gettime)
     mov     x8, __NR_clock_gettime
     svc     #0
 
@@ -11,4 +11,5 @@
     b.hi    __set_errno
 
     ret
-END(clock_gettime)
+END(__clock_gettime)
+.hidden __clock_gettime
diff --git a/libc/arch-arm64/syscalls/gettimeofday.S b/libc/arch-arm64/syscalls/__gettimeofday.S
similarity index 77%
rename from libc/arch-arm64/syscalls/gettimeofday.S
rename to libc/arch-arm64/syscalls/__gettimeofday.S
index 3b6104b..6582c49 100644
--- a/libc/arch-arm64/syscalls/gettimeofday.S
+++ b/libc/arch-arm64/syscalls/__gettimeofday.S
@@ -2,7 +2,7 @@
 
 #include <private/bionic_asm.h>
 
-ENTRY(gettimeofday)
+ENTRY(__gettimeofday)
     mov     x8, __NR_gettimeofday
     svc     #0
 
@@ -11,4 +11,5 @@
     b.hi    __set_errno
 
     ret
-END(gettimeofday)
+END(__gettimeofday)
+.hidden __gettimeofday