LinuxKPI: Finalize import of seq_file.

seq_file.h and linux_seq_file.c was imported form ports earlier but
linux_seq_file.c was never compiled in with the module. With this
commit base seq_file will replace ports seq_file and it required a
few modifications to not break functionality and build.

Reviewed by:	hps
Approved by:	imp (mentor), hps
MFC after:	1 week

sys/compat/linuxkpi/common/include/linux/seq_file.h

@@ -30,13 +30,29 @@
 #ifndef _LINUX_SEQ_FILE_H_
 #define _LINUX_SEQ_FILE_H_
 
+#include <linux/types.h>
+#include <linux/fs.h>
 #include <sys/sbuf.h>
 
-struct seq_operations;
-struct linux_file;
-
+#undef file
 #define inode vnode
 
+#define	DEFINE_SHOW_ATTRIBUTE(__name)					\
+static int __name ## _open(struct inode *inode, struct linux_file *file)	\
+{									\
+	return single_open(file, __name ## _show, inode->i_private);	\
+}									\
+									\
+static const struct file_operations __name ## _fops = {			\
+	.owner		= THIS_MODULE,					\
+	.open		= __name ## _open,				\
+	.read		= seq_read,					\
+	.llseek		= seq_lseek,					\
+	.release	= single_release,				\
+}
+
+struct seq_operations;
+
 struct seq_file {
 	struct sbuf	*buf;
 
@@ -67,5 +83,6 @@ int single_release(struct inode *, struct linux_file *);
 #define seq_puts(m, str)	sbuf_printf((m)->buf, str)
 #define seq_putc(m, str)	sbuf_putc((m)->buf, str)
 
+#define	file			linux_file
 
 #endif	/* _LINUX_SEQ_FILE_H_ */

sys/modules/linuxkpi/Makefile

@@ -13,6 +13,7 @@ SRCS=	linux_compat.c \
 	linux_pci.c \
 	linux_radix.c \
 	linux_rcu.c \
+	linux_seq_file.c \
 	linux_schedule.c \
 	linux_slab.c \
 	linux_tasklet.c \