tools/lib/lockdep: Enable -Wall by default

Regressions in liblockdep may be missed because it doesn't enable
warnings.

Adding -Wall immediately introduces a lot of warnings, but those will
be fixed by the following commits.

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/20170525130005.5947-5-alexander.levin@verizon.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>