tools/lib/lockdep: Remove -lpthread compiler option

tools/lib/lockdep: Remove -lpthread compiler option

With -lpthread option, the test for ABBA_2threads was
failing, and test passed if it was removed.
Since -pthread compiler option is sufficient for linking
to pthread libraries, this patch removes -lpthread.

Signed-off-by: Vishal Thanki <vishalthanki@gmail.com>
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
Cc: ben@decadent.org.uk
Link: http://lkml.kernel.org/r/20170525130005.5947-9-alexander.levin@verizon.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>