crypto.rand: use byteptr.vbytes instead of c_array_to_bytes_tmp (#8786)

vlib/crypto/rand/rand_solaris.c.v

@@ -14,27 +14,20 @@ const (
 
 // read returns an array of `bytes_needed` random bytes read from the OS.
 pub fn read(bytes_needed int) ?[]byte {
-	mut buffer := &byte(0)
-	unsafe {
-		buffer = malloc(bytes_needed)
-	}
-	mut bstart := buffer
+	mut buffer := unsafe { malloc(bytes_needed) }
 	mut bytes_read := 0
 	mut remaining_bytes := bytes_needed
 	// getrandom syscall wont block if requesting <= 256 bytes
 	for bytes_read < bytes_needed {
 		batch_size := if remaining_bytes > read_batch_size { read_batch_size } else { remaining_bytes }
-		unsafe {
-			bstart = buffer + bytes_read
-		}
-		rbytes := getrandom(batch_size, bstart)
+		rbytes := unsafe { getrandom(batch_size, buffer + bytes_read) }
 		if rbytes == -1 {
-			free(buffer)
+			unsafe { free(buffer) }
 			return read_error
 		}
 		bytes_read += rbytes
 	}
-	return c_array_to_bytes_tmp(bytes_needed, buffer)
+	return unsafe {buffer.vbytes(bytes_needed)}
 }
 
 fn v_getrandom(bytes_needed int, buffer voidptr) int {