add missing headers

This change adds some missing headers needed for compiling the
PandaBoard variant, which seems to not have seen a compiler for a
while.

Change-Id: Ifb54abb4dc676fafc29ecbae97bafaa547fcfc80

src/core/sal/panda/PandaTimer.ah

@@ -6,6 +6,8 @@
 
 #if defined(BUILD_PANDA)
 
+#include <assert.h>
+
 #include "../../../debuggers/openocd/openocd_wrapper.hpp"
 #include "PandaListener.hpp"
 

src/core/util/MemoryMap.cc

@@ -2,6 +2,7 @@
 #include <string>
 #include <sstream>
 #include <cassert>
+#include <stdlib.h>
 
 #include "MemoryMap.hpp"