fix an unintended behavior change in the type system rewrite, which caused us to...

fix an unintended behavior change in the type system rewrite, which caused us to compile
stuff like this:

typedef struct {
 int x, y, z;
} foo_t;

foo_t g;

into:
%"struct.<anonymous>" = type { i32, i32, i32 }
we now get:
%struct.foo_t = type { i32, i32, i32 }

This doesn't change the behavior of the compiler, but makes the IR much easier to read.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@134969 91177308-0d34-0410-b5e6-96231b3b80d8