Fix reopened #64812.
* typemanager.cs (Closure.Filter): Introduce checks for 'protected
internal'.
In tests:
* test-374.cs: New test based on #64812.
In errors:
* Makefile (%-lib.dll, %-module.dll): Build during 'make test' or
'make run-test'.
* cs0122-14.cs, cs0122-15.cs, CS0122-14-lib.cs, CS0122-15-lib.cs:
New tests based on #64812.
svn path=/trunk/mcs/; revision=44066