Remove key.h from portable files too.

Commit 5467fbcb removed key.h so stop including it in portable files
too.  Fixes builds on lots of platforms.

audit-bsm.c

@@ -49,7 +49,6 @@
 
 #include "ssh.h"
 #include "log.h"
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "xmalloc.h"

audit.c

@@ -31,7 +31,6 @@
 
 #include "audit.h"
 #include "log.h"
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 

auth-pam.c

@@ -88,7 +88,6 @@ extern char *__progname;
 #include "xmalloc.h"
 #include "sshbuf.h"
 #include "ssherr.h"
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "auth-pam.h"

auth-shadow.c

@@ -30,7 +30,6 @@
 #include <string.h>
 #include <time.h>
 
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "sshbuf.h"

auth-sia.c

@@ -37,7 +37,6 @@
 
 #include "ssh.h"
 #include "ssh_api.h"
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "auth-sia.h"

auth-skey.c

@@ -35,7 +35,6 @@
 #include <skey.h>
 
 #include "xmalloc.h"
-#include "key.h"
 #include "hostfile.h"
 #include "auth.h"
 #include "ssh-gss.h"