[Sanitizer] Add internal_isatty to sanitizer_libc and PrintsToTty to determine whether error reports are printed to terminal

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@167298 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/sanitizer_common/sanitizer_win.cc b/lib/sanitizer_common/sanitizer_win.cc
index 8919341..64b2202 100644
--- a/lib/sanitizer_common/sanitizer_win.cc
+++ b/lib/sanitizer_common/sanitizer_win.cc
@@ -154,6 +154,10 @@
   UNIMPLEMENTED();
 }
 
+int internal_isatty(fd_t fd) {
+  UNIMPLEMENTED();
+}
+
 fd_t internal_open(const char *filename, bool write) {
   UNIMPLEMENTED();
 }