MDL-30349 clear file stat cache when adding new theme cache files

Hopefully this will resolve some cache reset problems.

theme/image.php

@@ -115,6 +115,9 @@ if ($rev > -1) {
     $pathinfo = pathinfo($imagefile);
     $cacheimage = "$candidatelocation/$image.".$pathinfo['extension'];
     if (!file_exists($cacheimage)) {
+        // note: cache reset might have purged our cache dir structure,
+        //       make sure we do not use stale file stat cache in the next check_dir_exists()
+        clearstatcache();
         check_dir_exists(dirname($cacheimage));
         copy($imagefile, $cacheimage);
     }

theme/javascript.php

@@ -77,6 +77,9 @@ require_once('Minify.php');
 $theme = theme_config::load($themename);
 
 if ($rev > -1) {
+    // note: cache reset might have purged our cache dir structure,
+    //       make sure we do not use stale file stat cache in the next check_dir_exists()
+    clearstatcache();
     check_dir_exists(dirname($candidate));
     $fp = fopen($candidate, 'w');
     fwrite($fp, minify($theme->javascript_files($type)));

theme/styles.php

@@ -113,6 +113,9 @@ send_cached_css($candidatesheet, $rev);
 
 function store_css(theme_config $theme, $csspath, $cssfiles) {
     $css = $theme->post_process(minify($cssfiles));
+    // note: cache reset might have purged our cache dir structure,
+    //       make sure we do not use stale file stat cache in the next check_dir_exists()
+    clearstatcache();
     check_dir_exists(dirname($csspath));
     $fp = fopen($csspath, 'w');
     fwrite($fp, $css);