bug symfony#27669 [Filesystem] fix file lock on SunOS (fritzmg)

This PR was merged into the 2.8 branch.

Discussion
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[Filesystem] fix file lock on SunOS

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

See symfony#27668

Commits
-------

7adb641 fix file lock on SunOS

Author: nicolas-grekas

src/Symfony/Component/Filesystem/LockHandler.php

@@ -75,12 +75,12 @@ public function lock($blocking = false)
             $error = $msg;
         });
 
-        if (!$this->handle = fopen($this->file, 'r')) {
+        if (!$this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r')) {
             if ($this->handle = fopen($this->file, 'x')) {
                 chmod($this->file, 0444);
-            } elseif (!$this->handle = fopen($this->file, 'r')) {
+            } elseif (!$this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r')) {
                 usleep(100); // Give some time for chmod() to complete
-                $this->handle = fopen($this->file, 'r');
+                $this->handle = fopen($this->file, 'r+') ?: fopen($this->file, 'r');
             }
         }
         restore_error_handler();