* lisp/pcmpl-linux.el: Use lexical-binding.
(pcmpl-linux-fs-modules-path-format)
(pcmpl-linux-mtab-file): New constants.
(pcmpl-linux-fs-types, pcmpl-linux-mounted-directories): Use above
new constants.
* test/lisp/pcmpl-linux-resources/fs/ext4/.keep:
* test/lisp/pcmpl-linux-resources/mtab:
* test/lisp/pcmpl-linux-tests.el: New files.