tools: Use posix_memalign instead of valloc for NetBSD

More similar to other implementation.
posix_memalign was adde in NetBSD 8.0, released on July 17, 2018
and went out of support on May 4, 2024.

Signed-off-by: Frediano Ziglio <frediano.ziglio@cloud.com>
Acked-by: Anthony PERARD <anthony.perard@vates.tech>

tools/include/xenctrl.h

@@ -1390,6 +1390,11 @@ int xc_lockprof_query(xc_interface *xch,
                       uint64_t *time,
                       xc_hypercall_buffer_t *data);
 
+/**
+ * Allocate memory with a given alignment.
+ * The alignment must be a power of 2 and at least sizeof(void*).
+ * It returns NULL on error, errno is not set.
+ */
 void *xc_memalign(xc_interface *xch, size_t alignment, size_t size);
 
 /**

tools/libs/ctrl/xc_netbsd.c

@@ -60,7 +60,14 @@ void discard_file_cache(xc_interface *xch, int fd, int flush)
 
 void *xc_memalign(xc_interface *xch, size_t alignment, size_t size)
 {
-    return valloc(size);
+    int ret;
+    void *ptr;
+
+    ret = posix_memalign(&ptr, alignment, size);
+    if (ret != 0 || !ptr)
+        return NULL;
+
+    return ptr;
 }
 
 int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)