[compiler-rt] [NFCI] clarify that asan-*linux.cpp files affect *nix OS'es (PR #195565)

[Fangrui Song via llvm-commits]

================
@@ -8,7 +8,7 @@
 //
 // This file is a part of AddressSanitizer, an address sanity checker.
 //
-// Linux-specific malloc interception.
+// Linux-specific (and Unix/Unix-like) malloc interception.
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MaskRay wrote:

Since this is Unix-like, "Linux-specific" should be removed. 

https://github.com/llvm/llvm-project/pull/195565