[ODRHash] Skip some typedef types.

In some cases, a typedef only strips aways a keyword for a type, keeping the
same name as the root record type.  This causes some confusion when the type
is defined in one modules but only forward declared in another.  Skipping the
typedef and going straight to the record will avoid this issue.

typedef struct S {} S;
S* s;  // S is TypedefType here

struct S;
S* s;  // S is RecordType here

llvm-svn: 364119