Make putenv and getenv match the userland definition of these

functions, tweak man page and one variable that shouldn't be const
anymore.

Sponsored by: Netflix

stand/libsa/environment.c

@@ -162,7 +162,7 @@ setenv(const char *name, const char *value, int overwrite)
 }
 
 int
-putenv(const char *string)
+putenv(char *string)
 {
     char	*value, *copy;
     int		result;

stand/libsa/libstand.3

@@ -110,7 +110,7 @@ for set/unset hook functions.
 .Xc
 .It Xo
 .Ft int
-.Fn putenv "const char *string"
+.Fn putenv "char *string"
 .Xc
 .It Xo
 .Ft int

stand/libsa/stand.h

@@ -330,7 +330,7 @@ extern int		env_setenv(const char *name, int flags,
 extern char		*getenv(const char *name);
 extern int		setenv(const char *name, const char *value,
 			       int overwrite);
-extern int		putenv(const char *string);
+extern int		putenv(char *string);
 extern int		unsetenv(const char *name);
 
 extern ev_sethook_t	env_noset;		/* refuse set operation */

stand/userboot/test/test.c

@@ -367,10 +367,10 @@ test_getmem(void *arg, uint64_t *lowmem, uint64_t *highmem)
         *highmem = 0;
 }
 
-const char *
+char *
 test_getenv(void *arg, int idx)
 {
-	static const char *vars[] = {
+	static char *vars[] = {
 		"foo=bar",
 		"bar=barbar",
 		NULL

stand/userboot/userboot.h

@@ -202,7 +202,7 @@ struct loader_callbacks {
 	 * environment variable to return next. It will begin at 0 and
 	 * each invocation will add 1 to the previous value of 'num'.
 	 */
-	const char *	(*getenv)(void *arg, int num);
+	char *		(*getenv)(void *arg, int num);
 
 	/*
 	 * Version 4 additions.

stand/userboot/userboot/main.c

@@ -78,7 +78,7 @@ void
 loader_main(struct loader_callbacks *cb, void *arg, int version, int ndisks)
 {
 	static char mallocbuf[MALLOCSZ];
-	const char *var;
+	char *var;
 	int i;
 
 	if (version < USERBOOT_VERSION)

usr.sbin/bhyveload/bhyveload.c

@@ -529,7 +529,7 @@ addenv(const char *str)
 	SLIST_INSERT_HEAD(&envhead, env, next);
 }
 
-static const char *
+static char *
 cb_getenv(void *arg, int num)
 {
 	int i;