changes coming to the nyacc c99 parser

[Matt Wette]

Just to let nyacc c99 uses know ...

In the process of testing my "FFI Helper" I have found it necessary to 
expand the
nyacc c99 parser a bit.

First of all, thanks to Taylan for providing great support for his 
scheme-bytestructures
package.  This provide the C-Scheme compatibility needed to support 
calling into C
libraries.

I am currently working on generating a dbus mainloop from libdbus and 
epoll with the
ffi-helper.  It turns out that epoll used packed structures.  This means 
that the nyacc
c99 parser has to be upgraded to parse the gcc __attributes__ extension 
and this
structure needs to be carried up into the C-to-Scheme conversion 
process.  I still have
a bit of work to go but it turns out that scheme-bytestructures provided 
a flags for
specifying packed structures.   Away I go to get this working ...

struct epoll_event {
  uint32_t events;
  epoll_data_t data;
} __attribute__ ((__packed__));

=>

||    (decl (decl-spec-list
            (type-spec
              (struct-def
                (@ ("__packed__" ""))
                (ident "epoll_event")
                (field-list
                  (comp-decl
                    (decl-spec-list
                      (type-spec (typename "uint32_t")))
                    (comp-declr-list (comp-declr (ident "events"))))
                  (comp-decl
                    (decl-spec-list
                      (type-spec (typename "epoll_data_t")))
                    (comp-declr-list (comp-declr (ident "data"))))))))))