We were previously using :LONG, but that does not match the machine word
size on some platforms, namely Windows.

Bug reported by Anton Kovalenko.

Two fixes related to the change to the new syntax (:struct foo):
1) For size-of-* defconstant generation, emit with :struct.
2) Parse name and size in defcunion, not just leaving that to
notice-foreign-union-definition, because define-parse-method needs a
clean name.

Osicat now compiles cleanly.

Patch courtesy of pinterface. Fixes LP bug #852192.

In grovel file, write:

 (bitfield flags-ctype
   ((:flag-a "FLAG_A")
     :documentation "DOCU_A")
   ((:flag-b "FLAG_B")
     :documentation "DOCU_B")
   ((:flag-c "FLAG_C")
     :documentation "DOCU_C"))

And if the C header file has:

 #define FLAG_A 1
 #define FLAG_B 2
 #define FLAG_C 4

This will generate:

 (cffi:defbitfield (flags-ctype)
   (:flag-a 1)
   (:flag-b 2)
   (:flag-c 4))

Don't use -fPIC on those systems

We already do look at CC in GROVEL::CC-COMPILE-AND-LINK.

The CONSTANT groveler form now takes an additional keyword argument
TYPE, which defaults to INTEGER. In order to grovel floats,
DOUBLE-FLOAT must be used.

Reported by Zach Smith, patch by Nikodemus Siivola.