Causes a javac error when converting emitted files to byte code.
Essentially, have a line in the compiler that does not re-emit for any
aliased structs or enums.  However, this means that we do re-emit for
non-aliased structs or enums that happened to be included from another
file.  This can lead to a bug:

In file1.rph:
Enum E_A {}
Struct S_A
{
    Enum E_A a;
}

In file2.rph:
alias Enum E_A as 'file1java.E_A';
...

In emitted version of file2, will still emit code for S_A.  However,
that code will point to Enum E_A, not the aliased version of E_A.
Java will not know how to find this and complain.
Forgot to add harness for test case.