Use proper define for sesman listen_port size

The size of the listen_port for sesman cannot exceed
XRDP_SOCKETS_MAXPATH. We should use this value rather than
an arbitrary value of 256.

sesman/libsesman/Makefile.am

@@ -4,6 +4,7 @@
 AM_CPPFLAGS = \
   -DXRDP_PAMCONF_PATH=\"${pamconfdir}\" \
   -DXRDP_CFG_PATH=\"${sysconfdir}/xrdp\" \
+  -DXRDP_SOCKET_ROOT_PATH=\"${socketdir}\" \
   -I$(top_srcdir)/libipm \
   -I$(top_srcdir)/common
 #  -DXRDP_SBIN_PATH=\"${sbindir}\" \

sesman/libsesman/sesman_config.h

@@ -31,6 +31,8 @@
 #include "list.h"
 #include "log.h"
 
+#include "xrdp_sockets.h"
+
 enum SESMAN_CFG_SESS_POLICY_BITS
 {
     /* If these two are set, they override everything else */
@@ -182,7 +184,7 @@ struct config_sesman
      * @var listen_port
      * @brief Listening port
      */
-    char listen_port[256];
+    char listen_port[XRDP_SOCKETS_MAXPATH];
     /**
      * @var enable_user_wm
      * @brief Flag that enables user specific wm