[clang] [llvm] [InstallAPI] Collect symbols from ObjC Ivars (PR #83632)

[Juergen Ributzka via cfe-commits]

================
@@ -27,12 +27,40 @@ __attribute__((objc_exception))
 @interface Exception 
 @end
 
+
+//--- Foo.framework/PrivateHeaders/Foo_Private.h
+#import <Foo/Foo.h>
+
+ at interface ClassWithIvars : Visible  {
----------------
ributzka wrote:

```
@interface ClassWithIvars : Visible  {
@package 
  int _internalIVar;
@protected
  int _externalIVar;
@private
  int _privateIVar;
@public
char _ivar1;
 char _ivar2;
}
@end

@interface Exception () {
@public 
  char _ivarFromExtension;
}
@end
```

https://github.com/llvm/llvm-project/pull/83632