system/core: using equivalent code to fix build break for win host am: 1e61274532
am: 78d173ed25

Change-Id: I1b07f98c3e817b67567aacb2cd19ec2567f933e8
diff --git a/libutils/Unicode.cpp b/libutils/Unicode.cpp
index b2ded07..6e31ce4 100644
--- a/libutils/Unicode.cpp
+++ b/libutils/Unicode.cpp
@@ -484,7 +484,9 @@
     if (ret_difference >= 5) {
         // Log the difference between new and old calculation. A high number, or equal numbers
         // appearing frequently, would be indicative of an attack.
-        std::string logged_string = (std::ostringstream() << ret_difference).str();
+        std::ostringstream logged_string_stream;
+        logged_string_stream << ret_difference;
+        std::string logged_string = logged_string_stream.str();
         android_errorWriteWithInfoLog(0x534e4554, "29250543", -1 /* int_uid */,
             logged_string.c_str(), logged_string.length() + 1);
     }