tools/lib/lockdep: Fix 'set but not used' warnings

liblockdep defines trivial macros for working with interrupt flags, as
interrupts are never disabled in userland.  This results in warnings
from gcc when -Wunused-but-set-variable is enabled, and it is enabled
by -Wall.  Fix this by evaluating the flags parameter and casting it to
void.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: a.p.zijlstra@chello.nl
Link: http://lkml.kernel.org/r/20170525130005.5947-7-alexander.levin@verizon.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

tools/lib/lockdep/uinclude/linux/irqflags.h

@@ -17,19 +17,19 @@
 #define raw_local_irq_disable() do { } while (0)
 #define raw_local_irq_enable() do { } while (0)
 #define raw_local_irq_save(flags) ((flags) = 0)
-#define raw_local_irq_restore(flags) do { } while (0)
+#define raw_local_irq_restore(flags) ((void)(flags))
 #define raw_local_save_flags(flags) ((flags) = 0)
-#define raw_irqs_disabled_flags(flags) do { } while (0)
+#define raw_irqs_disabled_flags(flags) ((void)(flags))
 #define raw_irqs_disabled() 0
 #define raw_safe_halt()
 
 #define local_irq_enable() do { } while (0)
 #define local_irq_disable() do { } while (0)
 #define local_irq_save(flags) ((flags) = 0)
-#define local_irq_restore(flags) do { } while (0)
+#define local_irq_restore(flags) ((void)(flags))
 #define local_save_flags(flags)	((flags) = 0)
 #define irqs_disabled() (1)
-#define irqs_disabled_flags(flags) (0)
+#define irqs_disabled_flags(flags) ((void)(flags), 0)
 #define safe_halt() do { } while (0)
 
 #define trace_lock_release(x, y)