vtysh: fix build failure for certain case

The build failed if two conditions are met at the same time:

1. Configure with `--disable-dependency-tracking`
2. Set an indenpendent build directory

```
anlan@host:~/frr/build$ make
make: Entering directory '/home/anlan/frr/build'
true
/usr/bin/perl ../vtysh/daemons.pl zebra bgpd ripd ripngd ospfd ospf6d isisd fabricd nhrpd ldpd babeld eigrpd  pimd pim6d pbrd staticd bfdd vrrpd pathd > vtysh/vtysh_daemons.h
/bin/bash: line 1: vtysh/vtysh_daemons.h: No such file or directory
make: *** [Makefile:17644: vtysh/vtysh_daemons.h] Error 1
make: Leaving directory '/home/anlan/frr/build'
```

`~/frr/` is source directory, `~/frr/build/` is the specified build
directory.

So, just create necessary directory - `vtysh/`.

Signed-off-by: anlan_cs <vic.lan@pica8.com>

diff --git a/vtysh/subdir.am b/vtysh/subdir.am
index cc2a70ade63619114fe1be39c8af372735be9ca8..72204201d9249285892ff1049d7d47e91028ec3f 100644 (file)
--- a/vtysh/subdir.am
+++ b/vtysh/subdir.am
@@ -37,4 +37,5 @@ $(vtysh_vtysh_OBJECTS): vtysh/vtysh_daemons.h
 
 CLEANFILES += vtysh/vtysh_daemons.h
 vtysh/vtysh_daemons.h:
+       mkdir -p vtysh
        $(PERL) $(top_srcdir)/vtysh/daemons.pl $(vtysh_daemons) > vtysh/vtysh_daemons.h