Add missing includes for gcc 4.3.
See: http://gcc.gnu.org/gcc-4.3/porting_to.html

diff -Naur libmxp-0.2.2.orig/src/cmxpstate.cpp libmxp-0.2.2/src/cmxpstate.cpp
--- libmxp-0.2.2.orig/src/cmxpstate.cpp	2009-02-18 22:00:54.739236864 -0800
+++ libmxp-0.2.2/src/cmxpstate.cpp	2009-02-18 22:02:30.385272745 -0800
@@ -25,6 +25,7 @@
 
 #include <algorithm>
 #include <stdlib.h>
+#include <cstring>
 
 cMXPState::cMXPState (cResultHandler *resh, cElementManager *elm, cEntityManager *enm)
 {