[libFuzzer][Windows] Clean up RawPrint

Summary:
Use `_write` instead of the deprecated alias `write` on Windows.
Also, remove comment saying RawPrint is untested on Windows.

Reviewers: vitalybuka

Reviewed By: vitalybuka

Subscribers: vitalybuka

Differential Revision: https://reviews.llvm.org/D57589

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@353108 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/FuzzerIOWindows.cpp b/FuzzerIOWindows.cpp
index 79dacd9..e45c137 100644
--- a/FuzzerIOWindows.cpp
+++ b/FuzzerIOWindows.cpp
@@ -333,8 +333,7 @@
 }
 
 void RawPrint(const char *Str) {
-  // Not tested, may or may not work. Fix if needed.
-  write(2, Str, strlen(Str));
+  _write(2, Str, strlen(Str));
 }
 
 }  // namespace fuzzer