Add support for uncompressing to iovecs (scatter I/O).

Windows does not have struct iovec defined anywhere,
so we define our own version that's equal to what UNIX
typically has.

The bulk of this patch was contributed by Mohit Aron.

R=jeff


git-svn-id: https://snappy.googlecode.com/svn/trunk@76 03e5f5b5-db94-4691-08a0-1a8bf15f6143

snappy-stubs-public.h.in

@@ -44,6 +44,10 @@
 #include <stddef.h>
 #endif
 
+#if @ac_cv_have_sys_uio_h@
+#include <sys/uio.h>
+#endif
+
 #define SNAPPY_MAJOR @SNAPPY_MAJOR@
 #define SNAPPY_MINOR @SNAPPY_MINOR@
 #define SNAPPY_PATCHLEVEL @SNAPPY_PATCHLEVEL@
@@ -80,6 +84,15 @@ typedef std::string string;
   TypeName(const TypeName&);               \
   void operator=(const TypeName&)
 
+#if !@ac_cv_have_sys_uio_h@
+// Windows does not have an iovec type, yet the concept is universally useful.
+// It is simple to define it ourselves, so we put it inside our own namespace.
+struct iovec {
+	void* iov_base;
+	size_t iov_len;
+};
+#endif
+
 }  // namespace snappy
 
 #endif  // UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_PUBLIC_H_