Remove unnecessary includes of spinlock.h under include/linux

Remove the obviously unnecessary includes of <linux/spinlock.h> under the
include/linux/ directory, and fix the couple errors that are introduced as
a result of that.

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 1980867..7c8c6d8 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -52,6 +52,7 @@
 #ifdef __KERNEL__
 
 #include <linux/kref.h>
+#include <linux/spinlock.h>
 
 #define IPCMNI 32768  /* <= MAX_INT limit for ipc arrays (including sysctl changes) */