[clang] [clang][analyzer] Bring alpha.security.MmapWriteExec checker out of alpha package (PR #102636)

[Balázs Kéri via cfe-commits]

balazske wrote:

I have tested it on some of the projects but there are not results from this checker. The detected type of bug looks unlikely so it is difficult to test the checker this way.

https://github.com/llvm/llvm-project/pull/102636