SVN r325920 breaks build

[Michael Butler]

As follows ..

--- kern_mutex.o ---
/usr/src/sys/kern/kern_mutex.c:633:22: error: passing 'volatile struct 
thread *' to parameter of type 'struct thread *' discards qualifiers 
[-Werror,-Wincompatible-pointer-types-discards-qualifiers]
                 turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE);
                                    ^~~~~
/usr/src/sys/sys/turnstile.h:104:56: note: passing argument to parameter 
here
void    turnstile_wait(struct turnstile *, struct thread *, int);
                                                           ^
/usr/src/sys/kern/kern_mutex.c:1013:2: error: use of undeclared 
identifier 'v'
         v = MTX_READ_VALUE(m);
         ^
/usr/src/sys/kern/kern_mutex.c:1015:6: error: use of undeclared 
identifier 'v'
         if (v & MTX_RECURSED) {
             ^
/usr/src/sys/kern/kern_mutex.c:1024:6: error: use of undeclared 
identifier 'v'
         if (v == tid && _mtx_release_lock(m, tid))
             ^
4 errors generated.
*** [kern_mutex.o] Error code 1

	imb