minor symfony#13509 [2.3] [HttpFoundation] [MimeTypeGuesser] Updated exception in MimeTypeGuesser (phansys)

This PR was merged into the 2.3 branch.

Discussion
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[2.3] [HttpFoundation] [MimeTypeGuesser] Updated exception in MimeTypeGuesser

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#12857
| License       | MIT
| Doc PR        | none

Updated exception message in MimeTypeGuesser when no guessers available
(issue symfony#12857).

Commits
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1e4a8d5 [2.3] [HttpFoundation] [MimeTypeGuesser]

Author: fabpot

src/Symfony/Component/HttpFoundation/File/MimeType/MimeTypeGuesser.php

@@ -120,7 +120,11 @@ public function guess($path)
         }
 
         if (!$this->guessers) {
-            throw new \LogicException('Unable to guess the mime type as no guessers are available (Did you enable the php_fileinfo extension?)');
+            $msg = 'Unable to guess the mime type as no guessers are available';
+            if (!FileinfoMimeTypeGuesser::isSupported()) {
+                $msg .= ' (Did you enable the php_fileinfo extension?)';
+            }
+            throw new \LogicException($msg);
         }
 
         foreach ($this->guessers as $guesser) {