[clang] [clang][analyzer] Move checker alpha.unix.StdCLibraryFunctions out of alpha. (PR #66207)

[Balazs Benics via cfe-commits]

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@@ -1026,6 +1026,100 @@ Check for null pointers being passed as arguments to C string functions:
    return strlen(0); // warn
  }
 
+.. _unix-StdCLibraryFunctions:
+
+unix.StdCLibraryFunctions (C)
+"""""""""""""""""""""""""""""""""""
+Check for calls of standard library functions that violate predefined argument
+constraints. For example, it is stated in the C standard that for the ``int
+isalnum(int ch)`` function the behavior is undefined if the value of ``ch`` is
+not representable as unsigned char and is not equal to ``EOF``.
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steakhal wrote:

Char and unsigned are not escaped like we usually do for code.

https://github.com/llvm/llvm-project/pull/66207