[PATCH] Minor POSIX-fixes for udev

[PATCH] Minor POSIX-fixes for udev

The attached patch contains a few patches against udev, to remove
use of various XSI:isms and bash:isms, and to change two scripts form
/bin/bash to /bin/sh.  None of the bash-scripts in test/ uses any
bash-specific functions as far as I know, but I didn't touch them since
they aren't used runtime.

Rationale:
* Both of the /bin/bash-scripts are totally free from bashisms, hence they
  don't need to be /bin/bash; using /bin/sh instead helps (mainly)
  embedded-people

* local and source are bash:isms (well, they exist in several other
  shells as well, but they aren't part of POSIX or any of its extensions)

* -a in tests is an XSI-extension, not part of strict POSIX, and is
  easily replaced by &&
  | http://www.opengroup.org/onlinepubs/009695399/utilities/test.html

* Use of fgrep is deprecated in POSIX in favour of grep -F (though fgrep
  will remain in use for a long time...)
  | http://www.opengroup.org/onlinepubs/009695399/utilities/grep.html

The fgrep-change isn't really necessary, since fgrep can always be
implemented as a shell-script, but the rest of the changes would really
be appreciated.