Module Debugging: Fine-tune the condition that determines whether a type

Module Debugging: Fine-tune the condition that determines whether a type
can be found in a module.

There are externally visible anonymous types that can be found:
  typedef struct { } s; // I can be found via the typedef.
There are anonymous internal types that can be found:
  namespace { struct s {}; } // I can be found by name.

rdar://problem/24199640

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@258272 91177308-0d34-0410-b5e6-96231b3b80d8