filesystem_win.cc: change include of Shlobj.h to shlobj.h (#9686)

Firestore/core/src/util/filesystem_win.cc

@@ -18,7 +18,7 @@
 
 #if defined(_WIN32)
 
-#include <Shlobj.h>
+#include <shlobj.h>
 #include <windows.h>
 
 #include <cerrno>