fs/base: fix misc memory leak

as reported by Coverity with CID 72202

ompi/mca/fs/base/fs_base_get_parent_dir.c

@@ -10,6 +10,8 @@
  * Copyright (c) 2004-2005 The Regents of the University of California.
  *                         All rights reserved.
  * Copyright (c) 2008-2011 University of Houston. All rights reserved.
+ * Copyright (c) 2015      Research Organization for Information Science
+ *                         and Technology (RIST). All rights reserved.
  * $COPYRIGHT$
  * 
  * Additional copyrights may follow
@@ -64,9 +66,8 @@ void mca_fs_base_get_parent_dir ( char *filename, char **dirnamep)
 	 * or not.
 	 */
 	int namelen;
-	char *linkbuf;
+	char linkbuf[PATH_MAX+1];
 
-	linkbuf = malloc(PATH_MAX+1);
 	namelen = readlink(filename, linkbuf, PATH_MAX+1);
 	if (namelen == -1) {
 	    /* something strange has happened between the time that
@@ -79,7 +80,6 @@ void mca_fs_base_get_parent_dir ( char *filename, char **dirnamep)
 	    /* successfully read the link */
 	    linkbuf[namelen] = '\0'; /* readlink doesn't null terminate */
 	    dir = strdup(linkbuf);
-	    free(linkbuf);
 	}
     }