Get rid of indirect include of fs_struct.h

Don't pull it in sched.h; very few files actually need it and those
can include directly.  sched.h itself only needs forward declaration
of struct fs_struct;

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/proc/task_nommu.c

@@ -2,6 +2,7 @@
 #include <linux/mm.h>
 #include <linux/file.h>
 #include <linux/fdtable.h>
+#include <linux/fs_struct.h>
 #include <linux/mount.h>
 #include <linux/ptrace.h>
 #include <linux/seq_file.h>