proc: unsigned file descriptors

Make struct proc_inode::fd unsigned.

This allows better code generation on x86_64 (less sign extensions).

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/proc/internal.h

@@ -60,7 +60,7 @@ union proc_op {
 
 struct proc_inode {
 	struct pid *pid;
-	int fd;
+	unsigned int fd;
 	union proc_op op;
 	struct proc_dir_entry *pde;
 	struct ctl_table_header *sysctl;