asan/msan/tsan: fix broken linux syscalls

Currently the following source code:

u64 NanoTime() {
  kernel_timeval tv = {};
  internal_syscall(__NR_gettimeofday, &tv, 0);
  return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
}

generates the following assembly:

Dump of assembler code for function __sanitizer::NanoTime():
=> 0x00007ff30657d380 <+0>:	lea    -0x10(%rsp),%rdi
   0x00007ff30657d385 <+5>:	xor    %esi,%esi
   0x00007ff30657d387 <+7>:	mov    $0x60,%eax
   0x00007ff30657d38c <+12>:	syscall 
   0x00007ff30657d38e <+14>:	mov    $0,%eax
   0x00007ff30657d393 <+19>:	retq   

with this change:

Dump of assembler code for function __sanitizer::NanoTime():
=> 0x00007faab834f380 <+0>:	movq   $0x0,-0x10(%rsp)
   0x00007faab834f389 <+9>:	movq   $0x0,-0x8(%rsp)
   0x00007faab834f392 <+18>:	lea    -0x10(%rsp),%rdi
   0x00007faab834f397 <+23>:	xor    %esi,%esi
   0x00007faab834f399 <+25>:	mov    $0x60,%eax
   0x00007faab834f39e <+30>:	syscall 
   0x00007faab834f3a0 <+32>:	mov    -0x8(%rsp),%rax
   0x00007faab834f3a5 <+37>:	mov    -0x10(%rsp),%rcx
   0x00007faab834f3aa <+42>:	imul   $0x3e8,%rax,%rdx
   0x00007faab834f3b1 <+49>:	imul   $0x3b9aca00,%rcx,%rax
   0x00007faab834f3b8 <+56>:	add    %rdx,%rax
   0x00007faab834f3bb <+59>:	retq   

llvm-svn: 191908