kern-tools: handle directories with, or without, trailing /

kern-tools: handle directories with, or without, trailing /

Robert P. J. Day reported that configuration fragments and kernel
features were not being found when organized in a particular manner:

  linux
   - $BOARD
       - mm.patch
       - mm.scc
   - ssd_sil.cfg
   - ssd_sil.patch
   - ssd_sil.scc
   - uio.cfg
   .. etc

There was a bug in the tools that did not handle the mix of subdirs
properly and ended up leaving a trailing / on the elements *not* in
the $BOARD subdir. As a result, the configuration fragments were not
properly found when searching the include paths, and a configuration
failure was triggered (due to missing files).

This change tweaks the tools to always check a path with and without
a trailing / when processing config fragments so they can be later
found when processing the configuration of the kernel.

Reported-by: "Robert P. J. Day" <rpjday@crashcourse.ca>
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>