Added WTSAPI32.DLL.

diff --git a/configure.ac b/configure.ac
index b7acb6a..e83fa2d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1703,6 +1703,7 @@
 dlls/wintrust/Makefile
 dlls/wow32/Makefile
 dlls/wsock32/Makefile
+dlls/wtsapi32/Makefile
 dlls/x11drv/Makefile
 documentation/Makefile
 fonts/Makefile