[libcxx-commits] [libcxx] Remove incorrect forward-declaration of lgamma_r header (PR #80979)

[Louis Dionne via libcxx-commits]

================
@@ -297,6 +297,10 @@ long double    truncl(long double x);
 #    pragma GCC system_header
 #  endif
 
+#  if defined(__APPLE__)
----------------
ldionne wrote:

```suggestion
// This is required to define functions like lgamma_r on Apple platforms.
// These functions are not required by the Standard but our implementation
// uses them.
#  if defined(__APPLE__) && !defined(_REENTRANT)
```

https://github.com/llvm/llvm-project/pull/80979