threads: implement support for spinlock (WebAssembly#324)

Author: loganek

Makefile

@@ -262,6 +262,11 @@ LIBC_TOP_HALF_MUSL_SOURCES += \
         thread/pthread_setcancelstate.c \
         thread/pthread_setspecific.c \
         thread/pthread_self.c \
+        thread/pthread_spin_destroy.c \
+        thread/pthread_spin_init.c \
+        thread/pthread_spin_lock.c \
+        thread/pthread_spin_trylock.c \
+        thread/pthread_spin_unlock.c \
         thread/pthread_testcancel.c \
         thread/sem_destroy.c \
         thread/sem_getvalue.c \

expected/wasm32-wasi-threads/defined-symbols.txt

@@ -1044,6 +1044,11 @@ pthread_rwlockattr_setpshared
 pthread_self
 pthread_setcancelstate
 pthread_setspecific
+pthread_spin_destroy
+pthread_spin_init
+pthread_spin_lock
+pthread_spin_trylock
+pthread_spin_unlock
 pthread_testcancel
 pthread_timedjoin_np
 pthread_tryjoin_np