Suppress warning in compile-time

```
In end of data:
php-mode.el:1864:1:Warning: the function ‘pkg-info-version-info’ is not
    known to be defined.
```

Author: zonuexe

Diff for: php-mode.el

@@ -92,6 +92,7 @@
 
 (eval-when-compile
   (require 'regexp-opt)
+  (autoload 'pkg-info-version-info "pkg-info")
   (defvar c-vsemi-status-unknown-p)
   (defvar syntax-propertize-via-font-lock))