Allow generic "BasicType" in alias this declaration

[dlangBugzillaToGithub]

monarchdodra reported this on 2013-11-14T12:44:14Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=11517

Description

Just like a standard alias, as opposed to only "Identifier".

Right now:
AliasThisDeclaration:
    alias Identifier this

Request:
AliasThisDeclaration:
    alias Identifier this
    alias BasicType this

See also:
https://d.puremagic.com/issues/show_bug.cgi?id=8735

For example:
struct Foo
{
    int test(string op)() { return 0; }
    alias test!"*" this;
}