[ASAN] Removed special case controlling allocator constants for __aarch64__.

[kstoimenov]

Summary

This patch should land before D137136 to make sure that the leak sanitizer allocator works correctly. This patch is NFC without D137136.

[vitalybuka]

Please include that this patch is NFC as without D137136 SANITIZER_CAN_USE_ALLOCATOR64 is 0

[vitalybuka]

into description and git commit
note that editing description here does not update the stuff which will be in git commit

[kstoimenov]

Updated description.

[kstoimenov]

Moved NFC comment to the summary.

compiler-rt/lib/asan/asan_allocator.h

 // Android needs to support 39, 42 and 48 bit VMA.
 const uptr kAllocatorSpace =  ~(uptr)0;
 const uptr kAllocatorSize  =  0x2000000000ULL;  // 128G.
 typedef VeryCompactSizeClassMap SizeClassMap;
 #elif SANITIZER_RISCV64
 const uptr kAllocatorSpace = ~(uptr)0;
 const uptr kAllocatorSize = 0x2000000000ULL;  // 128G.
 typedef VeryDenseSizeClassMap SizeClassMap;
-# elif defined(__aarch64__)
-// AArch64/SANITIZER_CAN_USE_ALLOCATOR64 is only for 42-bit VMA
-// so no need to different values for different VMA.
-const uptr kAllocatorSpace =  0x10000000000ULL;
-const uptr kAllocatorSize  =  0x10000000000ULL;  // 3T.
-typedef DefaultSizeClassMap SizeClassMap;
 #elif defined(__sparc__)
 const uptr kAllocatorSpace = ~(uptr)0;
 const uptr kAllocatorSize = 0x20000000000ULL;  // 2T.
 typedef DefaultSizeClassMap SizeClassMap;
 # elif SANITIZER_WINDOWS
 const uptr kAllocatorSpace = ~(uptr)0;
 const uptr kAllocatorSize  =  0x8000000000ULL;  // 500G
 typedef DefaultSizeClassMap SizeClassMap;