bsd-user: align use of mmap_lock to that of linux-user

The introduction of stricter mmap_lock checking in translate-all broke
the BSD user build. The working mmap_lock functions were hidden behind
CONFIG_USE_NPTL which is never defined. This patch brings them inline
with linux-user.

Despite the disapearence of the comment "We aren't threadsafe to start
with..." this doesn't make bsd-user so. It will still need the rest of
the fixes that have been done in linux-user ported over.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c
index 1ad018a..7f2018e 100644
--- a/bsd-user/mmap.c
+++ b/bsd-user/mmap.c
@@ -24,8 +24,7 @@
 
 //#define DEBUG_MMAP
 
-#if defined(CONFIG_USE_NPTL)
-pthread_mutex_t mmap_mutex;
+static pthread_mutex_t mmap_mutex = PTHREAD_MUTEX_INITIALIZER;
 static int __thread mmap_lock_count;
 
 void mmap_lock(void)
@@ -62,16 +61,6 @@
     else
         pthread_mutex_unlock(&mmap_mutex);
 }
-#else
-/* We aren't threadsafe to start with, so no need to worry about locking.  */
-void mmap_lock(void)
-{
-}
-
-void mmap_unlock(void)
-{
-}
-#endif
 
 /* NOTE: all the constants are the HOST ones, but addresses are target. */
 int target_mprotect(abi_ulong start, abi_ulong len, int prot)