BUG: headers with BUG/BUG_ON etc. need linux/bug.h

If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including <linux/bug.h> and not just
expecting it to be implicitly present.

We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index 44f1514..5ff2df6 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -3,6 +3,7 @@
 
 #include <linux/types.h>
 #include <linux/string.h>
+#include <linux/bug.h>
 #include <linux/mutex.h>
 #include <linux/cpumask.h>
 #include <linux/nodemask.h>