Fix T102225: Crash opening menus

Seems to be introduced by 99e5024e97.

The crash is caused by the difference in the expected alignment
of the `uiPopupMenu` which is 16 bytes and the actual alignment
returned by the `MEM_mallocN()` which is 8 bytes due to the memory
head.

Now made it so that `MEM_new()` can be used for types with any
alignment.

Differential Revision: https://developer.blender.org/D16375

intern/guardedalloc/MEM_guardedalloc.h

@@ -271,7 +271,7 @@ void MEM_use_guarded_allocator(void);
 template<typename T, typename... Args>
 inline T *MEM_new(const char *allocation_name, Args &&...args)
 {
-  void *buffer = MEM_mallocN(sizeof(T), allocation_name);
+  void *buffer = MEM_mallocN_aligned(sizeof(T), alignof(T), allocation_name);
   return new (buffer) T(std::forward<Args>(args)...);
 }