Fix build on Macos

Author: dkhalanskyjb

core/darwin/src/TimeZoneNative.kt

@@ -64,6 +64,6 @@ internal actual fun currentSystemDefaultZone(): RegionTimeZone {
     */
     NSTimeZone.resetSystemTimeZone()
     val zone = NSTimeZone.systemTimeZone
-    val zoneId = zone.name ?: throw IllegalStateException("Failed to get the system timezone")
+    val zoneId = zone.name
     return RegionTimeZone(systemTzdb.rulesForId(zoneId), zoneId)
 }

core/native/src/Instant.kt

@@ -134,7 +134,7 @@ private fun isValidInstantSecond(second: Long) = second >= MIN_SECOND && second
 
 internal fun currentTime(): Instant = memScoped {
     val tm = alloc<timespec>()
-    val error = clock_gettime(CLOCK_REALTIME, tm.ptr)
+    val error = clock_gettime(CLOCK_REALTIME.convert(), tm.ptr)
     check(error == 0) { "Error when reading the system clock: ${strerror(errno)}" }
     try {
         require(tm.tv_nsec in 0 until NANOS_PER_ONE)