Use internal_memset to initialize this variable.

Otherwise, the compiler may use memset in non-optimized builds, which is
forbidden in the nolibc part of the runtime.

llvm-svn: 193098

compiler-rt/lib/sanitizer_common/sanitizer_linux.cc

@@ -218,7 +218,8 @@ uptr GetTid() {
 }
 
 u64 NanoTime() {
-  kernel_timeval tv = {};
+  kernel_timeval tv;
+  internal_memset(&tv, 0, sizeof(tv));
   internal_syscall(__NR_gettimeofday, &tv, 0);
   return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
 }