Unlike some other OSes, OpenIndiana and OmniOS programs
for poweroff/halt/reboot/shutdown are under /usr/sbin
which is stand-alone, and are not visible under /sbin
expected by qemu hard-coded paths across many versions.

Also note that there is no `hwclock` here (to fix later).

Signed-off-by: Jim Klimov <jim@jimklimov.com>

diff -Naur qemu-11.1.1.orig/qga/commands-posix.c qemu-11.1.1/qga/commands-posix.c
--- qemu-11.1.1.orig/qga/commands-posix.c	2026-10-01 17:15:50.925986296 +0200
+++ qemu-11.1.1/qga/commands-posix.c	2026-10-01 18:11:49.626078563 +0200
@@ -220,9 +220,14 @@
     return retcode;
 }
 
-#define POWEROFF_CMD_PATH "/sbin/poweroff"
-#define HALT_CMD_PATH "/sbin/halt"
-#define REBOOT_CMD_PATH "/sbin/reboot"
+/* NOTE: This build is configured for illumos distros where /usr/sbin and
+ *  /usr/bin are separate directories (possibly filesystems) from /sbin
+ *  and /bin, which are unified and mashed together in some other OSes.
+ */
+#define POWEROFF_CMD_PATH "/usr/sbin/poweroff"
+#define HALT_CMD_PATH "/usr/sbin/halt"
+#define REBOOT_CMD_PATH "/usr/sbin/reboot"
+#define SHUTDOWN_CMD_PATH "/usr/sbin/shutdown"
 
 void qmp_guest_shutdown(const char *mode, Error **errp)
 {
@@ -266,7 +271,7 @@
         return;
     }
 
-    const char *argv[] = {"/sbin/shutdown",
+    const char *argv[] = {SHUTDOWN_CMD_PATH,
 #ifdef CONFIG_SOLARIS
                           shutdown_flag, "-g0", "-y",
 #elif defined(CONFIG_BSD)
@@ -299,6 +304,7 @@
     int ret;
     Error *local_err = NULL;
     struct timeval tv;
+    /* FIXME: On illumos, use `date` */
     const char *argv[] = {"/sbin/hwclock", has_time ? "-w" : "-s", NULL};
 
     /* If user has passed a time, validate and set it. */