[scudo][NFC] Remove unneeded template from scudo::CombinedAllocator

compiler-rt/lib/scudo/scudo_allocator.h

struct AP32 {
   static const uptr kFlags =
       SizeClassAllocator32FlagMasks::kRandomShuffleChunks |
       SizeClassAllocator32FlagMasks::kUseSeparateSizeClassForBatch;
 };
 typedef SizeClassAllocator32<AP32> PrimaryT;
 #endif  // SANITIZER_CAN_USE_ALLOCATOR64
 
 #include "scudo_allocator_secondary.h"
-#include "scudo_allocator_combined.h"
 
 typedef LargeMmapAllocator SecondaryT;
-typedef CombinedAllocator<PrimaryT, SecondaryT> BackendT;
-typedef BackendT::AllocatorCache AllocatorCacheT;
+
+#include "scudo_allocator_combined.h"
+
+typedef CombinedAllocator BackendT;
+typedef CombinedAllocator::AllocatorCache AllocatorCacheT;
 
 void initScudo();
 
 void *scudoAllocate(uptr Size, uptr Alignment, AllocType Type);
 void scudoDeallocate(void *Ptr, uptr Size, uptr Alignment, AllocType Type);
 void *scudoRealloc(void *Ptr, uptr Size);
 void *scudoCalloc(uptr NMemB, uptr Size);
 void *scudoValloc(uptr Size);
 void *scudoPvalloc(uptr Size);
 int scudoPosixMemalign(void **MemPtr, uptr Alignment, uptr Size);
 void *scudoAlignedAlloc(uptr Alignment, uptr Size);
 uptr scudoMallocUsableSize(void *Ptr);
 
 }  // namespace __scudo
 
 #endif  // SCUDO_ALLOCATOR_H_

compiler-rt/lib/scudo/scudo_allocator_combined.h

 
 #ifndef SCUDO_ALLOCATOR_COMBINED_H_
 #define SCUDO_ALLOCATOR_COMBINED_H_
 
 #ifndef SCUDO_ALLOCATOR_H_
 # error "This file must be included inside scudo_allocator.h."
 #endif
 
-template <class PrimaryAllocator, class SecondaryAllocator>
 class CombinedAllocator {
  public:
+  using PrimaryAllocator = PrimaryT;
+  using SecondaryAllocator = SecondaryT;
   using AllocatorCache = typename PrimaryAllocator::AllocatorCache;
   void init(s32 ReleaseToOSIntervalMs) {
     Primary.Init(ReleaseToOSIntervalMs);
     Secondary.Init();
     Stats.Init();
   }
 
   // Primary allocations are always MinAlignment aligned, and as such do not