Use which instead of whereis (#11407)

which searches in PATH
whereis -b doesn't exist on some OSes

LibreNMS/Config.php

@@ -535,13 +535,10 @@ class Config
     public static function locateBinary($binary)
     {
         if (!str_contains($binary, '/')) {
-            $output = `whereis -b $binary`;
-            $list = trim(substr($output, strpos($output, ':') + 1));
-            $targets = explode(' ', $list);
-            foreach ($targets as $target) {
-                if (is_executable($target)) {
-                    return $target;
-                }
+            $target = trim(`which $binary`);
+
+            if (!empty($target)) {
+                return $target;
             }
         }
         return $binary;