[compiler-rt] [hwasan] Add fixed_shadow_base flag (PR #73980)

[Vitaly Buka via llvm-commits]

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@@ -84,3 +84,10 @@ HWASAN_FLAG(bool, malloc_bisect_dump, false,
 // are untagged before the call.
 HWASAN_FLAG(bool, fail_without_syscall_abi, true,
             "Exit if fail to request relaxed syscall ABI.")
+
+HWASAN_FLAG(
+    uptr, fixed_shadow_base, 0,
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vitalybuka wrote:

-1, not sure that none will need NULL as a base

https://github.com/llvm/llvm-project/pull/73980