Update Windows logging.h based on 2df0ca34

Commit changes to src/windows/glog/logging.h that were missed in
2df0ca34. Because a change to src/glog/logging.h.in was made,
src/windows/preprocess.sh needed to be run.

src/windows/glog/logging.h

@@ -1117,6 +1117,12 @@ class GOOGLE_GLOG_DLL_DECL LogStreamBuf : public std::streambuf {
   LogStreamBuf(char *buf, int len) {
     setp(buf, buf + len - 2);
   }
+
+  // Resets the buffer. Useful if we reuse it by means of TLS.
+  void reset() {
+     setp(pbase(), epptr());
+  }
+
   // This effectively ignores overflow.
   virtual int_type overflow(int_type ch) {
     return ch;
@@ -1179,6 +1185,7 @@ public:
     size_t pcount() const { return streambuf_.pcount(); }
     char* pbase() const { return streambuf_.pbase(); }
     char* str() const { return pbase(); }
+    void reset() { streambuf_.reset(); }
 
   private:
     LogStream(const LogStream&);