code cleanup: 0 --> NULL

intern/memutil/MEM_Allocator.h

@@ -63,7 +63,7 @@ struct MEM_Allocator
 	// NB: __n is permitted to be 0.  The C++ standard says nothing
 	// about what the return value is when __n == 0.
 	_Tp* allocate(size_type __n, const void* = 0) {
-		_Tp* __ret = 0;
+		_Tp* __ret = NULL;
 		if (__n)
 			__ret = static_cast<_Tp*>(
 				MEM_mallocN(__n * sizeof(_Tp),

intern/memutil/MEM_CacheLimiter.h

@@ -108,7 +108,7 @@ public:
 	bool destroy_if_possible() {
 		if (can_destroy()) {
 			delete data;
-			data = 0;
+			data = NULL;
 			unmanage();
 			return true;
 		}

intern/memutil/intern/MEM_CacheLimiterC-Api.cpp

@@ -128,7 +128,7 @@ MEM_CacheLimiterCClass::~MEM_CacheLimiterCClass()
 {
 	// should not happen, but don't leak memory in this case...
 	for (list_t::iterator it = cclass_list.begin(); it != cclass_list.end(); it++) {
-		(*it)->set_data(0);
+		(*it)->set_data(NULL);
 
 		delete *it;
 	}