Auto merge of #1441 - scoopr:fix_namespace_macro, r=emilio

Fix namespaces with macro names

This fixes
1. When the name of the namespace is actually a `#define` macro, which previosly got the name of the macro
2. When the namespace is started from a included file (the header is wrapped in a `nsbegin.h`/`nsend.h` includes), which previously got generated name for the namespace

The change is small, but I feel it is a bit of a hack. It wasn't obvious to me what is a better path though.