[clang] [clang][analyzer] Move 'alpha.core.FixedAddressDereference' out of alpha (PR #132404)

[Donát Nagy via cfe-commits]

================
@@ -97,6 +97,41 @@ core.DivideZero (C, C++, ObjC)
 .. literalinclude:: checkers/dividezero_example.c
     :language: c
 
+.. _core-FixedAddressDereference:
+
+core.FixedAddressDereference (C, C++, ObjC)
+"""""""""""""""""""""""""""""""""""""""""""
+Check for dereferences of fixed addresses.
+
+A pointer contains a fixed address if it was set to a hard-coded value or it
+becomes otherwise obvious that at that point it can have only a single specific
+value.
----------------
NagyDonat wrote:

```suggestion
numerical value.
```
To clarify that something like
```
int global;
void foo(int *p) {
  if (p != &global)
    return;
  // ...
}
```
is not considered to be a "single specific value".

https://github.com/llvm/llvm-project/pull/132404