Add missing <ostream> include

It's currently included by string_piece.h, but that include is going
away.

Bug: crashpad:none
Change-Id: Ia2e22fa60cf4a1dafe54e2c8fcc054a29235fad3
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3015681
Commit-Queue: Hans Wennborg <hans@chromium.org>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
GitOrigin-RevId: e481b16bf411407c4497e6a4cb01e2a9cae20a10
diff --git a/util/win/get_function.cc b/util/win/get_function.cc
index 3d00a7a..91a9165 100644
--- a/util/win/get_function.cc
+++ b/util/win/get_function.cc
@@ -14,6 +14,8 @@
 
 #include "util/win/get_function.h"
 
+#include <ostream>
+
 #include "base/check.h"
 #include "base/strings/utf_string_conversions.h"