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

[Clement Courbet 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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legrosbuffle wrote:

We should not be relying on the fact that BenchmarkRunner.cpp includes Target.h. Let's move these definitions to a separate file (e.g. MMap.h) and include that file in files that use these symbols.

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