radix-tree tests: properly initialize mutex

The pthread_mutex_t in regression1.c wasn't being initialized properly.

Link: http://lkml.kernel.org/r/20160815194237.25967-4-ross.zwisler@linux.intel.comSigned-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/radix-tree/regression1.c

@@ -43,7 +43,7 @@
 #include "regression.h"
 
 static RADIX_TREE(mt_tree, GFP_KERNEL);
-static pthread_mutex_t mt_lock;
+static pthread_mutex_t mt_lock = PTHREAD_MUTEX_INITIALIZER;
 
 struct page {
 	pthread_mutex_t lock;