Include stdlib.h where its functions are used

Fixes build failure on OS X 10.10 and 10.11:

error: use of undeclared identifier 'free'
error: use of undeclared identifier 'malloc'
error: use of undeclared identifier 'qsort'

AerofoilPortable/GpThreadEvent_Cpp11.cpp

@@ -1,5 +1,7 @@
 #include "GpThreadEvent_Cpp11.h"
 
+#include <stdlib.h>
+
 GpThreadEvent_Cpp11::GpThreadEvent_Cpp11(bool autoReset, bool startSignaled)
 	: m_flag(startSignaled)
 	, m_autoReset(autoReset)

AerofoilX/GpLogDriver_X.cpp

@@ -4,6 +4,7 @@
 #include "GpApplicationName.h"
 #include "GpIOStream.h"
 
+#include <stdlib.h>
 #include <time.h>
 #include <cstring>
 

PortabilityLayer/ZipFileProxy.cpp

@@ -10,6 +10,7 @@
 #include "DeflateCodec.h"
 
 #include <algorithm>
+#include <stdlib.h>
 
 namespace
 {