freestanding: sys_getuid, sys_waitid; minimal fork check; remove bare.S

vlib/os/bare/bare_example_linux.v

@@ -1,20 +1,7 @@
-fn syscall5(number, arg1, arg2, arg3, arg4, arg5 voidptr) voidptr
-
-fn write(fd int, data voidptr, nbytes int) int {
-	return 	 syscall5(
-          1, // SYS_write
-           fd,
-            data,
-            nbytes,
-            0, // ignored
-            0  // ignored
-        )
-}
-
 fn main() {
-	write(1, c'hello\n', 6)
-	s := 'test string'
-	write(1, s.str, s.len)
+	sys_write(1, 'hello\n'.str, 6)
+	s := 'test string\n'
+	sys_write(1, s.str, u64(s.len))
 	a := s[0]
+	println("Hello freestanding!")
 }
-