Remove a number of unneeded import os/bb calls

The bb and os modules are always imported so having these extra import calls
are a waste of space/execution time. They also set a bad example for people
copy and pasting code so clean them up.

(From OE-Core rev: 7d674820958be3a7051ea619effe1a6061d9cbe2)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/package.bbclass

@@ -444,7 +444,7 @@ python perform_packagecopy () {
 # seeding this list with reasonable defaults, then load from
 # the fs-perms.txt files
 python fixup_perms () {
-    import os, pwd, grp
+    import pwd, grp
 
     # init using a string with the same format as a line as documented in
     # the fs-perms.txt file