[2998]] Corrects a build error under Solaris10 SunStudio where use of

getenv requires include of stdlib.h in src/bin/d2/d2_controller.cc

src/bin/d2/d2_controller.cc

@@ -16,6 +16,8 @@
 #include <d2/d2_process.h>
 #include <d2/spec_config.h>
 
+#include <stdlib.h>
+
 namespace isc {
 namespace d2 {