stand: Make ioctl declaration consistent

It typically had two args with an optional third from the userland
declaration in sys/ioccom.h. However, the funciton definition used a
non-optional char * argument. This mismatch is UB behavior (but worked
due to the calling convetions of all our machines).

Instead, add a declaration for ioctl to stand.h, make the third arg
'void *' which is a better match to the ... declaration before. This
prevents the convert int * -> char * errors as well. Make the ioctl
user-space declaration truly user-space specific (omit it in the
stand-alone build).

No functional change intended.

Sponsored by:		Netflix
Reviewed by:		emaste
Differential Revision:	https://reviews.freebsd.org/D37680

stand/libsa/ioctl.c

@@ -66,7 +66,7 @@ __FBSDID("$FreeBSD$");
 #include "stand.h"
 
 int
-ioctl(int fd, u_long cmd, char *arg)
+ioctl(int fd, u_long cmd, void *arg)
 {
 	struct open_file *f;
 

stand/libsa/stand.h

@@ -315,6 +315,7 @@ extern int	close(int);
 extern void	closeall(void);
 extern ssize_t	read(int, void *, size_t);
 extern ssize_t	write(int, const void *, size_t);
+extern int	ioctl(int, u_long, void *);
 extern struct	dirent *readdirfd(int);
 extern void	preload(int);
 

sys/sys/ioccom.h

@@ -82,7 +82,7 @@
 #define	_IOC_INVALID	(_IOC_VOID|_IOC_INOUT)	/* Never valid cmd value,
 						   use as filler */
 
-#else
+#elif !defined(_STANDALONE)
 
 #include <sys/cdefs.h>