initial OpenBSD support

core/sys/unix/pthread_openbsd.odin

@@ -0,0 +1,65 @@
+//+build openbsd
+package unix
+
+import "core:c"
+
+pthread_t             :: distinct rawptr
+pthread_attr_t        :: distinct rawptr
+pthread_mutex_t       :: distinct rawptr
+pthread_mutexattr_t   :: distinct rawptr
+pthread_cond_t        :: distinct rawptr
+pthread_condattr_t    :: distinct rawptr
+pthread_rwlock_t      :: distinct rawptr
+pthread_rwlockattr_t  :: distinct rawptr
+pthread_barrier_t     :: distinct rawptr
+pthread_barrierattr_t :: distinct rawptr
+pthread_spinlock_t    :: distinct rawptr
+
+pthread_key_t  :: distinct c.int
+pthread_once_t :: struct {
+	state: c.int,
+	mutex: pthread_mutex_t,
+}
+
+PTHREAD_MUTEX_ERRORCHECK :: 1
+PTHREAD_MUTEX_RECURSIVE  :: 2
+PTHREAD_MUTEX_NORMAL     :: 3
+PTHREAD_MUTEX_STRICT_NP  :: 4
+
+PTHREAD_DETACHED      :: 0x1
+PTHREAD_SCOPE_SYSTEM  :: 0x2
+PTHREAD_INHERIT_SCHED :: 0x4
+PTHREAD_NOFLOAT       :: 0x8
+
+PTHREAD_CREATE_DETACHED :: PTHREAD_DETACHED
+PTHREAD_CREATE_JOINABLE :: 0
+PTHREAD_SCOPE_PROCESS   :: 0
+PTHREAD_EXPLICIT_SCHED  :: 0
+
+SCHED_FIFO  :: 1
+SCHED_OTHER :: 2
+SCHED_RR    :: 3
+
+sched_param :: struct {
+	sched_priority: c.int,
+}
+
+sem_t :: distinct rawptr
+
+foreign import libc "system:c"
+
+@(default_calling_convention="c")
+foreign libc {
+	sem_open :: proc(name: cstring, flags: c.int) -> ^sem_t ---
+
+	sem_init :: proc(sem: ^sem_t, pshared: c.int, initial_value: c.uint) -> c.int ---
+	sem_destroy :: proc(sem: ^sem_t) -> c.int ---
+	sem_post :: proc(sem: ^sem_t) -> c.int ---
+	sem_wait :: proc(sem: ^sem_t) -> c.int ---
+	sem_trywait :: proc(sem: ^sem_t) -> c.int ---
+	//sem_timedwait :: proc(sem: ^sem_t, timeout: time.TimeSpec) -> c.int ---
+
+	// NOTE: unclear whether pthread_yield is well-supported on Linux systems,
+	// see https://linux.die.net/man/3/pthread_yield
+	pthread_yield :: proc() ---
+}

core/sys/unix/pthread_unix.odin

@@ -1,4 +1,4 @@
-//+build linux, darwin, freebsd
+//+build linux, darwin, freebsd, openbsd
 package unix
 
 foreign import "system:pthread"