GUACAMOLE-861: Fixes WINDOWS_TIME calculation
This fixes the UNIX time to FILETIME conversion in WINDOWS_TIME macro,
according to MSDN (addition instead of subtraction).
diff --git a/src/protocols/rdp/rdp_fs.h b/src/protocols/rdp/rdp_fs.h
index e8299ef..f1e4295 100644
--- a/src/protocols/rdp/rdp_fs.h
+++ b/src/protocols/rdp/rdp_fs.h
@@ -188,7 +188,7 @@
* Converts a UNIX timestamp (seconds since Jan 1, 1970 UTC) to Windows
* timestamp (100 nanosecond intervals since Jan 1, 1601 UTC).
*/
-#define WINDOWS_TIME(t) ((t - ((uint64_t) 11644473600)) * 10000000)
+#define WINDOWS_TIME(t) ((t + ((uint64_t) 11644473600)) * 10000000)
/**
* An arbitrary file on the virtual filesystem of the Guacamole drive.
