Tweaks to namei.c, need testing

I am in the process of optimizing some things I've found in 
elks/fs/minix/namei.c to reduce code size and improve performance. The 
changes are primarily of the sort where a dereference or a calculation 
is used multiple times and can be consolidated down to a single 
operation that is cached instead. I've made other miscellaneous changes 
that should work fine, but those I am a little more concerned about.

Please feel free to test and make sure everything still works with 
latest git. I may make more optimization changes like these over the 
next 24 hours, so git pull before you git commit.

-Jody