bug #4453 Fix preg_match error on 7.4snapshot (kubawerlos)

This PR was merged into the 2.12 branch.

Discussion
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Fix preg_match error on 7.4snapshot

[Error](https://travis-ci.org/FriendsOfPHP/PHP-CS-Fixer/jobs/549345318).

Commits
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638ad04 Fix preg_match error on 7.4snapshot

Author: SpacePossum

src/Fixer/ControlStructure/NoSuperfluousElseifFixer.php

@@ -84,7 +84,7 @@ private function convertElseifToIf(Tokens $tokens, $index)
         $whitespace = '';
         for ($previous = $index - 1; $previous > 0; --$previous) {
             $token = $tokens[$previous];
-            if ($token->isWhitespace() && Preg::match('/(\R[^\R]*)$/', $token->getContent(), $matches)) {
+            if ($token->isWhitespace() && Preg::match('/(\R\V*)$/', $token->getContent(), $matches)) {
                 $whitespace = $matches[1];
 
                 break;