base: forward declare struct _stat for Windows

We need to forward declare the struct as otherwise the definition is
local to the declaration and cannot be defined.  This addresses the
`-Wvisibility` warning when building for Windows.

Author: compnerd

CoreFoundation/Base.subproj/CoreFoundation_Prefix.h

@@ -287,7 +287,9 @@ void OSMemoryBarrier();
 #define CF_PRIVATE extern
 
 #define __builtin_expect(P1,P2) P1
-    
+
+#include <sys/stat.h>
+
 // These are replacements for POSIX calls on Windows, ensuring that the UTF8 parameters are converted to UTF16 before being passed to Windows
 CF_EXPORT int _NS_stat(const char *name, struct _stat *st);
 CF_EXPORT int _NS_mkdir(const char *name);

CoreFoundation/Base.subproj/ForFoundationOnly.h

@@ -422,8 +422,14 @@ typedef CFTypeRef _Nonnull (*CFErrorUserInfoKeyCallBack)(CFErrorRef err, CFStrin
 CF_EXPORT void CFErrorSetCallBackForDomain(CFStringRef domainName, CFErrorUserInfoKeyCallBack _Nullable callBack) API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
 CF_EXPORT CFErrorUserInfoKeyCallBack _Nullable CFErrorGetCallBackForDomain(CFStringRef domainName) API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
 
-#if DEPLOYMENT_TARGET_WINDOWS
+_CF_EXPORT_SCOPE_END
+
 // ---- Windows-specific material ---------------------------------------
+#if DEPLOYMENT_TARGET_WINDOWS
+
+#include <sys/stat.h>
+
+_CF_EXPORT_SCOPE_BEGIN
 
 // These are replacements for POSIX calls on Windows, ensuring that the UTF8 parameters are converted to UTF16 before being passed to Windows
 CF_EXPORT int _NS_stat(const char *name, struct _stat *st);
@@ -436,10 +442,11 @@ CF_EXPORT char *_NS_getenv(const char *name);
 CF_EXPORT int _NS_rename(const char *oldName, const char *newName);
 CF_EXPORT int _NS_open(const char *name, int oflag, int pmode);
 CF_EXPORT int _NS_mkstemp(char *name, int bufSize);
-#endif
 
 _CF_EXPORT_SCOPE_END
 
+#endif
+
 // ---- Miscellaneous material ----------------------------------------
 
 _CF_EXPORT_SCOPE_BEGIN