Silence errors on unlink for when tests are run in parallel.

tests/013-read-filehandle-file-stream.phpt

@@ -24,7 +24,7 @@ $imagick->readImageFile($handle);
 echo "Width: " . $imagick->getImageWidth() . "\n";
 echo "Height: " . $imagick->getImageHeight() . "\n";
 
-unlink($file);
+@unlink($file);
 
 echo 'success';
 

tests/013-read-filehandle.phpt

@@ -19,7 +19,7 @@ $imagick->clear();
 $handle = fopen($file, 'rb');
 $imagick->readImageFile($handle);
 
-unlink($file);
+@unlink($file);
 
 echo 'success';
 

tests/031_Imagick_affineTransformImage_basic.phpt

@@ -134,7 +134,9 @@ echo "Ok";
 --CLEAN--
 <?php
 $f = __DIR__ . "/test_031.png";
-if (file_exists($f)) unlink($f);
+if (file_exists($f)) {
+    @unlink($f);
+}
 ?>
 --EXPECTF--
 Checking white

tests/257_Imagick_setImageChannelMask_basic.phpt

@@ -31,7 +31,9 @@ echo "Ok";
 --CLEAN--
 <?php
 $f = __DIR__ . '/maskTest.png';
-if (file_exists($f)) unlink($f);
+if (file_exists($f)) {
+    unlink($f);
+}
 ?>
 --EXPECTF--
 Ok

tests/264_ImagickDraw_getTextDirection_basic.phpt

@@ -65,7 +65,9 @@ echo "Ok";
 --CLEAN--
 <?php
 $f = __DIR__ . '/directionTest.png';
-if (file_exists($f)) unlink($f);
+if (file_exists($f)) {
+    unlink($f);
+}
 ?>
 --EXPECTF--
 Ok

tests/274_imagick_setImageAlpha.phpt

@@ -71,7 +71,9 @@ echo "Ok";
 --CLEAN--
 <?php
 $f = __DIR__ . '/setAlphaTest.png';
-if (file_exists($f)) unlink($f);
+if (file_exists($f)) {
+    @unlink($f);
+}
 ?>
 --EXPECTF--
 Ok

tests/281_imagick_houghLineImage_basic.phpt

@@ -30,7 +30,9 @@ echo "Ok";
 --CLEAN--
 <?php
 $f = __DIR__ . '/houghline_output_image.png';
-if (file_exists($f)) unlink($f);
+if (file_exists($f)) {
+    @unlink($f);
+}
 ?>
 --EXPECTF--
 Ok