[llvm] [llvm-exegesis] Refactor MMAP platform-specific preprocessor directives (PR #75422)

[Aiden Grossman via llvm-commits]

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@@ -32,6 +32,21 @@
 #include "llvm/TargetParser/SubtargetFeature.h"
 #include "llvm/TargetParser/Triple.h"
 
+// Before kernel 4.17, Linux did not support MAP_FIXED_NOREPLACE, so if it is
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boomanaiden154 wrote:

Good point. Moved over to `MmapUtils.h`.

https://github.com/llvm/llvm-project/pull/75422